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SCIENCE TERM - II
Written as per the syllabus prescribed by the Central Board of Secondary Education.
CBSECLASS X
Salient Features
• Extensive coverage of the syllabus for Term - II in an effortless and easy to grasp format.
• In alignment with the latest paper pattern of Central Board of Secondary Education.
• Neat and labelled diagrams.
• Variety of additional questions important for the Assessment.
• ‘Enrich your knowledge’ familiarises you with facts.
• Memory maps at the end of each chapter to facilitate quick revision.
• Formative Assessment at the end of each chapter.
• Sample Test Paper at the end of each chapter designed for student’s Self Assessment.
• Questions from previous years board papers have been solved.
• Model Question Papers in accordance with the latest paper pattern.
10420_11040_JUP
P.O. No. 34470
Printed at: Repro Knowledgecast Ltd., Mumbai
© Target Publications Pvt. Ltd. No part of this book may be reproduced or transmitted in any form or by any means, C.D. ROM/Audio Video Cassettes or electronic, mechanical
including photocopying; recording or by any information storage and retrieval system without permission in writing from the Publisher.
PREFACE
In the case of good books, the point is not how many of them you can get through, but rather how many can get through to you. “Class X: Science” is a complete and thorough guide critically analyzed and extensively drafted to foster the student’s confidence. The book ensures extensive coverage of the syllabus for Term - II in an effortless and easy to grasp format. The CBSE course structure is mainly divided into two parts: Summative assessment and Formative assessment.
The Topic-wise classified format for each chapter of this book helps the students in easy comprehension.
Each chapter includes the following features:
Chapter at a glance provides a brief theory of every subtopic at the start of each chapter. MCQs, NCERT Exercises and Activities, Intext and Exemplar Questions along-with the answers are covered. Questions – answers have been classified into Very Short Answer Questions, Short Answer Questions:
Type I, Short Answer Questions : Type –II , Long Answer Questions along-with the marks allocation. Neatly labelled diagrams have been provided wherever required. Higher Order Thinking Skills (HOTS) questions have been added for the student to gain insight on the various levels of theory-based questions. Value - based Questions which emphasize on values along-with knowledge have been included. Memory Map has been provided to give a quick overview of the chapter, helping the students in effective learning. Sample Test Papers help test the range of preparation of the student and the amount of knowledge of each chapter. ‘Enrich Your Knowledge’ help the students gain knowledge required to understand different concepts.
Two Model Question Papers, designed as per CBSE Paper Pattern, are a unique tool to enable self-assessment for the students. Formative assessment cover a range of activities and problems. Answers for previous years Board Questions have been included in this book. The journey to create a complete book is strewn with triumphs, failures and near misses. If you think we’ve nearly missed something or want to applaud us for our triumphs, we’d love to hear from you.
Please write to us on : [email protected] A book affects eternity; one can never tell where its influence stops.
Best of luck to all the aspirants! Yours faithfully,
Publisher
UNIT WISE WEIGHTAGE (Term ‐ II)
No. Units Marks
I Chemical substances - Nature and behaviour 23
II World of living 30
III Natural Phenomena 29
V Natural resources 08
Total 90
Unit I: Chemical Substances - Nature and Behaviour
Carbon compounds: Covalent bonding in carbon compounds, Versatile nature of carbon, Homologous
series, Nomenclature of carbon compounds containing functional groups (halogens, alcohols, ketones,
aldehydes, alkanes, alkenes and alkynes), difference between saturated hydrocarbons and unsaturated
hydrocarbons, Chemical properties of carbon compounds (combustion, oxidation, addition and substitution
reactions), Ethanol and ethanoic acid (only properties and uses), Soaps and detergents.
Periodic classification of elements: Need for classification, Modern Periodic Table, gradation in properties,
valency, atomic number, metallic and non-metallic properties.
Unit II: World of Living
Reproduction: Reproduction in animals and plants (asexual and sexual), reproductive health-need for and
methods of family planning. Safe sex vs HIV/AIDS. Child bearing and women’s health.
Heredity and Evolution: Heredity; Mendel’s contribution-Laws inheritance of traits: Sex determination:
Brief introduction; Basic concepts of evolution.
Unit III: Natural Phenomena
Reflection of light at curved surfaces, images formed by spherical mirrors, centre of curvature, principal axis,
principal focus, focal length, mirror formula (Derivation not required), magnification.
Refraction; Laws of refraction, refractive index.
Refraction of light by spherical lens, image formed by spherical lenses, lens formula (Derivation not
required), magnification. Power of a lens; Functioning of a lens in human eye, defects of vision and their
corrections, applications of spherical mirrors and lenses.
Refraction of light through a prism, dispersion of light, scattering of light, applications in daily life.
Unit V: Natural Resources
Conservation of natural resources: Management of natural resources. Conservation and judicious use of
natural resources. Forest and wild life, coal and petroleum conservation. Examples of people’s participation
for conservation of natural resources.
Regional environment: Big dams: advantages and limitations; alternatives, if any. Water harvesting.
Sustainability of natural resources.
Our environment: Eco-system, environmental problems, ozone depletion, waste production and their
solutions. Biodegradable and non-biodegradable substances.
PRACTICALS (Term ‐ II)
List of experiments 1. To study the following properties of acetic acid (ethanoic acid): a. odour b. solubility in water c. effect on litmus d. reaction with sodium bicarbonate 2. To study saponification reaction for preparation of soap. 3. To study the comparative cleaning capacity of a sample of soap in soft and hard water. 4. To determine the focal length of: a. Concave mirror, b. Convex lens, by obtaining the image of a distant object. 5. To trace the path of a ray of light passing through a rectangular glass slab for different angles of
incidence. Measure the angle of incidence, angle of refraction, angle of emergence and interpret the result.
6. To study (a) binary fission in Amoeba and (b) budding in Yeast with the help of prepared slides. 7. To trace the path of the rays of light through a glass prism. 8. To find the image distance for varying object distances in case of a convex lens and draw
corresponding ray diagrams to show the nature of image formed. 9. To study homology and analogy with the help of models/charts of animals and
models/charts/specimens of plants. 10. To identify the different parts of an embryo of a dicot seed (Pea, gram or red kidney bean).
QUESTION PAPER
PATTER
N
(%)
Wei
ghta
ge
15%
26%
23%
12%
25%
100%
Tot
al
Mar
ks
11
19
17
9 19
75 (
24)
15 (
12)
90 (
36)
Lon
g A
nsw
er
5 M
ark
s
1 1 1 1 2
65=
30
-
65=
30
Sh
ort
An
swer
-II
3 M
ark
s
1 4 4 - 3
123
=36
-
123
=36
Sh
ort
An
swer
-I
2 M
ark
s
- 1 - 2 -
32=
6
32=
6
62=
12
Ver
y S
hor
t A
ns.
1 M
ark
3 - - - -
31=
3
91=
9
121
=12
Lea
rnin
g O
utc
omes
an
d T
esti
ng
Com
pete
ncie
s
R
easo
ning
Ana
lytic
al
Ski
lls
C
riti
cal
Thi
nkin
g S
kills
et
c.
Typ
olog
y of
Qu
esti
ons
Rem
emb
erin
g –
(Kn
owle
dge
bas
ed s
impl
e re
call
qu
estio
ns, t
o kn
ow s
peci
fic
fact
s, te
rms,
con
cept
s, p
rinc
iple
s or
theo
ries
; Ide
ntif
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efin
e, o
r re
cite
, inf
orm
atio
n)
Un
der
stan
din
g –
(Com
pre
hen
sion
– to
be
fam
ilia
r w
ith
mea
ning
and
to u
nder
stan
d co
ncep
tual
ly, i
nter
pret
, com
pare
, co
ntra
st, e
xpla
in, p
arap
hras
e or
inte
rpre
t inf
orm
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Ap
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(U
se a
bstr
act i
nfor
mat
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in c
oncr
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situ
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app
ly k
now
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e to
new
situ
atio
ns; U
se g
iven
co
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t to
inte
rpre
t a s
ituat
ion,
pro
vide
an
exam
ple
or s
olve
a
prob
lem
)
Hig
h O
rder
Th
ink
ing
skill
s –
(An
alys
is a
nd
Syn
thes
is –
C
lass
ify,
com
pare
, con
tras
t or
diff
eren
tiat
e be
twee
n di
ffer
ent p
iece
s of
info
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ion;
Org
aniz
e an
d/or
inte
grat
e un
ique
pie
ces
of in
form
atio
n fr
om a
var
iety
of
sour
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Eva
luat
ion
and
Mu
lti-
Dis
cip
linar
y (A
ppra
ise,
judg
e,
and/
or ju
stif
y th
e va
lue
or w
orth
of
a de
cisi
on o
r ou
tcom
es,
or to
pre
dict
out
com
es b
ased
on
valu
es)
Tot
al (
The
ory
Bas
ed Q
uest
ions
)
Pra
ctic
al B
ased
Que
stio
ns (
PB
Qs)
TO
TA
L
No.
01.
02.
03.
04.
05.
CONTENTS
NCERT Textbook
Chapter No. Chapter Name Page No.
04 Carbon and its Compounds 1
05 Periodic Classification of Elements 55
08 How do Organisms Reproduce 86
09 Heredity and Evolution 121
10 Light- Reflection and Refraction 155
11 The Human Eye and the Colourful World 202
15 Our Environment 232
16 Management of Natural Resources 256
Model Question Paper – I 275
Model Question Paper – II 279
1
Chapter 08: How do Organisms Reproduce?
Syllabus
4.0 Introduction
4.1 Bonding in carbon – The covalent bond
4.2 Versatile nature of carbon
4.3 Chemical properties of carbon compounds
4.4 Some important carbon compounds – Ethanol and ethanoic acid
4.5 Soaps and detergents Chapter At a Glance 4.0 Introduction Carbon is a versatile element. It is of immense importance to us in both its elemental form such as diamond, graphite, etc. and in its combined form such as petroleum, coal, etc.
It forms the basis of all living organisms and most of the things that we use or consume in our day-to-day life. The cotton used form making fabrics, the paper used for writing, the sugar we eat, are all made up of carbon compounds. In spite of the immense importance of carbon, only small amount of it is available in nature.
Occurrence PercentageEarth’s crust (in the form of minerals like carbonates, hydrogencarbonates, coal, petroleum, etc.)
0.02
Atmosphere (as carbon dioxide) 0.03 4.1 Bonding in carbon – The covalent bond Ionic compounds: The compounds formed by transfer of
electrons from a metal to a non-metal are known as ionic compounds.
Ionic compounds are/have: i. Solids and hard in nature. ii. High melting and boiling points. iii. Soluble in water and insoluble in organic (or
non-polar) solvents such as kerosene. iv. Conductors of electricity in molten state or in
its aqueous solution. However, in solid state, they do not conduct electricity.
Bonding in carbon compounds: i. The melting and boiling points of carbon
compounds are generally low as compared to ionic compounds.
Few examples of carbon compound are listed below:
Compound Formula Melting
point (K)
Boiling point (K)
a. Methane CH4 90 111 b. Ethanol CH3CH2OH 156 351 c. Chloroform CHCl3 209 334 d. Acetic acid CH3COOH 290 391
ii. Carbon compounds are generally poor
conductors of electricity. This suggests the bonding in these compounds do not give rise to any ions or charged particles that can conduct electricity.
iii. The atomic number of carbon (C) is 6. The number of electrons in K shell = 2 The number of electrons in L shell = 4 So, the electronic configuration of carbon is
(2, 4). iv. Carbon has four electrons in its outermost
shell. It could form C4 anion by gaining four
electrons and thus, completing its octet. However, it would be difficult for the nucleus of C4 anion having six protons to hold on to ten electrons.
It could form C4+ cation by losing four electrons and thus, completing its octet. However, it would be difficult to remove four electrons to form C4+ cation having six protons to hold on to just two electrons.
Hence, carbon atom shares its valence electrons with other atoms of carbon or with atoms of other elements, to attain noble gas configuration.
v. The shared electrons belong to the valence shells of both the atoms involved in bonding.
04. Carbon and its Compounds
2
Class X: Science
2
Covalent bond: i. The bond formed by the mutual sharing of
electrons between two combining atoms is known as covalent bond.
ii. Depending on the number of electron pairs shared between the two combining atoms, there are 3 types of covalent bonds.
a. Single covalent bond: Two combining atoms share one electron pair. It is
represented by a single line () between the two combining atoms.
b. Double covalent bond: Two combining atoms share two pairs of electrons. It is represented by a double line (=) between the two combining atoms.
c. Triple covalent bond: Two combining atoms share three pairs of electrons. It is
represented by a triple line () between the two combining atoms.
Covalent compounds: The compounds formed by mutual sharing of
electrons between the atoms are called covalent compounds.
Electron dot structures: i. Gilbert Newton Lewis (an American chemist)
introduced Lewis symbols or electron dot symbols. These are simple notations to represent the valence electrons of an atom.
ii. In these symbols, only the valence electrons are shown as dots or crosses surrounding the symbol of given element. Inner electrons are not shown in these symbols.
iii. The electron dot symbols of the elements of the first and second periods are:
iv. The important conditions for writing electron
dot structures of simple covalent molecules are as follows:
a. Each bond is formed as a result of sharing of an electron pair between the atoms.
b. Each combining atom contributes atleast one electron to the shared pair.
c. The combining atoms attain the outer shell noble gas configurations as a result of the sharing of electrons.
d. After accounting for the shared pairs of electrons for covalent bonds, the remaining electrons form lone pairs.
The electron dot structure of carbon tetrachloride (CCl4) can be represented as:
Some simple covalent compounds: i. Molecules having single covalent bond(s): a. Hydrogen molecule (H2): b. Chlorine molecule (Cl2): c. Water molecule (H2O): d. Ammonia molecule (NH3): e. Methane molecule (CH4):
Li , O ,B , He , Be , C , H , F , NeN ,
Cl
Cl
Cl
Cl C
H H ORH H
Single covalent bond between two hydrogen atoms
Single covalent bonds between nitrogen and hydrogen atoms
OR H N H
H
H H N
H
Single covalent bond between two chlorine atoms
ORClCl ClCl
Single covalent bonds between carbon and hydrogen atoms
OR H C H
H
H
H C H
H
H
OR H O HH O H
Single covalent bonds between oxygen and hydrogen atoms
3
Chapter 04: Carbon and its Compounds
ii. Molecules having double covalent bond(s): a. Oxygen molecule (O2): b. Carbon dioxide molecule (CO2): iii. Molecules having triple covalent bond(s): Nitrogen molecule (N2): Properties of covalent compounds: i. Physical state: Unlike ionic compounds
(which generally exist as solids), the covalent compounds exist in all the three states, i.e., solid, liquid and gaseous. These are generally organic compounds.
ii. Melting and boiling points: Covalent compounds have low melting and boiling points because the molecules in covalent compounds are held together by weak intermolecular forces.
iii. Electrical conductivity: Covalent compounds are poor conductors of electricity since they do not form ions when dissolved in a solvent or when melted.
iv. Solubility: Covalent compounds are generally soluble in non-polar solvents like carbon tetrachloride, benzene, etc. but insoluble in polar solvents like water.
Allotropes of carbon: i. Allotropy is the phenomenon in which an
element exists in different physical forms having different physical properties but similar chemical properties.
ii. Carbon occurs in several allotropic forms such as: Diamond, graphite, fullerenes, etc.
iii. Diamond – Tetrahedral arrangement of carbon atoms forming a rigid three-dimensional structure.
iv. Graphite – Hexagonal arrangement of carbon atoms forming a layered structure.
v. Fullerenes – Another class of carbon allotropes having spherical shape (such as C-60 Buckminsterfullerene also known as bucky ball) or cylindrical shape (such as carbon nanotubes).
4.2 Versatile nature of carbon Carbon forms a large number of compounds
because of its two unique properties: i. Catenation ii. Tetravalency Catenation: The unique property of carbon atom to form
covalent bonds with other carbon atoms giving rise to large molecules is called catenation. The compounds formed may have long straight chains of carbon, branched chains of carbon or rings of carbon. In these compounds, carbon atoms may form single, double or triple covalent bonds.
Tetravalency: Carbon has a valency of four (i.e., tetravalent).
Hence, it can form bonds with four other atoms of carbon or atoms of other monovalent elements. Carbon, being small in size, forms strong bonds with many elements such as hydrogen (H), oxygen (O), nitrogen (N), sulphur (S), chlorine (CI), etc.
Saturated carbon compounds: Carbon compounds in which the carbon atoms
are linked to each other by single bonds are called saturated carbon compounds.
eg. Ethane (C2H6), Propane (C3H8), etc. Unsaturated carbon compounds: Carbon compounds having atleast one carbon-
carbon double or triple bond are called unsaturated carbon compounds.
eg. Ethene (C2H4), Ethyne (C2H2), etc. Electron dot structures of some carbon
compounds:
Double covalent bond between two oxygen atoms
OR O O=O O
Triple covalent bond between two nitrogen atoms
OR N NN N
Double covalent bond between each oxygen atom and the carbon atom
OR O = C = OC OO
Electron dot structure of propane
H
H
H
H
H
C C x
x C C
x
x C C
H
H
H
C
CC
Electron dot structure of ethane
H
H
H
H
H
H
C C
H
4
Class X: Science
4
Steps to draw the structural formula of a
carbon compound: Step I – Link the carbon atoms together by a
single bond. Step II – Complete the tetravalency of carbon
atoms by forming single bonds with hydrogen atoms.
Step III – Complete the remaining valency of each carbon atom by forming double or triple bonds between the carbon atoms.
eg. Drawing the structural formula of ethene (C2H4):
Step I: C C Step II: Step III: Straight chain carbon compounds: In these compounds, carbon atoms are linked to
each other to form a straight continuous chain. eg.
Butane (or n-
Butane) C4H10
Pentane (or n-
Pentane) C5H12
Branched chain carbon compounds: In these compounds, carbon atoms are linked
to each other to form different branches in the structure.
eg.
Iso-butane
C4H10
Cyclic carbon compounds: In these compounds, carbon atoms are linked to
each other to form a ring (or a closed chain). eg.
Cyclohexane C6H12
Benzene C6H6
Hydrocarbons: i. Compounds containing only carbon and
hydrogen are known as hydrocarbons. eg. Methane (CH4), Ethane (C2H6), Ethene
(C2H4), etc. ii. Saturated hydrocarbons containing only
carbon-carbon single bonds are called alkanes. iii. Unsaturated hydrocarbons containing atleast
one carbon-carbon double bond are called alkenes.
iv. Unsaturated hydrocarbons containing atleast one carbon-carbon triple bond are called alkynes.
Isomerism: Compounds with identical molecular formula
but different structures are called isomers and the property is known as isomerism.
eg. Butane has molecular formula C4H10. It forms two isomers: n-butane and
isobutane. In n-butane, all carbon atoms are linked
in a straight chain. The structure of n-butane is: In isobutane, three carbon atoms are
linked in a straight chain and one carbon atom forms branched chain.
The structure of isobutane is:
H C C C C H
H H H H
H H H H
H C C C C C H
H H H H H
H H H H H
H C C C H
H
H
H
H C H
H
H
H
H
C
H
H HC
CC
C
C
H
H
H C C C C H
H H H H
H H HH
Electron dot structure of ethyne
H C H C
H
CC
H H H
CC
H H H H
C
H
H
H
H
C
H – C – C – H
H H
H – C = C – H
H H
H C C C H
H H H
H – C – H H H
H
Electron dot structure of ethene
H
H
H
H
C C
5
Chapter 04: Carbon and its Compounds
O
– C – H
O
– C –
O
– C – OH
Functional groups: i. In a hydrocarbon chain, one or more hydrogen
atoms can be replaced by heteroatoms like halogens, oxygen, nitrogen, etc., such that the valency of carbon remains satisfied.
ii. An atom or a group of atoms present in a molecule which determines characteristic chemical properties of the molecule is called a functional group.
iii. Functional groups give specific chemical properties to the compounds, regardless of the length and the nature of the carbon chain.
iv. Some of the functional groups in carbon compounds are as follows:
Sr. No.
Name of the functional group
Formula of the functional group
1. Chloro – Cl 2. Bromo – Br 3. Alcohol – OH
4. Aldehyde
5. Ketone
6. Carboxylic acid
Homologous series: A series of carbon compounds having the
same functional group, similar chemical properties and the successive members differing from each other in their molecular formula by a CH2 (methylene) unit is called homologous series.
Characteristics of homologous series: i. The general formula of all compounds in the
series is the same.
ii. They have the same functional group. iii. Physical properties like melting point, boiling
point, density, etc., generally show a gradual change with increase of molecular mass in the series.
iv. Chemical properties of the members of the series show close resemblance because of the presence of the same functional group in them.
v. Consecutive members of the series differ from one another by CH2 unit (methylene group), and their molecular weight differs by 14 units.
Homologous series of alkanes: General formula: CnH2n + 2 (where n =1, 2, 3,..)
1st member n = 1 CH4 (Methane) 2nd member n = 2 C2H6 (Ethane) 3rd member n = 3 C3H8 (Propane)
Homologous series of alkenes: General formula: CnH2n (where n = 2, 3, 4, …)
1st member n = 2 C2H4 (Ethene) 2nd member n = 3 C3H6 (Propene)3rd member n = 4 C4H8 (Butene)
Homologous series of alkynes: General formula: CnH2n2 (where n = 2,3,4,…)
1st member n = 2 C2H2 (Ethyne) 2nd member n = 3 C3H4 (Propyne) 3rd member n = 4 C4H6 (Butyne)
Nomenclature of carbon compounds: Rules for naming carbon compounds are as
follows: i. Select the longest chain of carbon atoms
containing the functional group. ii. Name the carbon chain based on the number
of carbon atoms in the longest chain. iii. Indicate the functional group (if present) in the
name of the compound with either a prefix or a suffix.
Functional group Prefix/Suffix
Chloro Prefix chloro Bromo Prefix bromo Alcohol Suffix ol Aldehyde Suffix al Ketone Suffix one Carboxylic acid Suffix oic acid Double bond(Alkene) Suffix ene Triple bond(Alkyne) Suffix yne
iv. If a suffix is to be added, then replace the final
‘e’ in the name of the carbon chain with the suffix.
v. If the carbon chain is unsaturated, then replace the final ‘ane’ in the name of the carbon chain with ‘ene’ for alkenes or ‘yne’ for alkynes.
Some functional groups are always present atthe end of the carbon chain.
eg. Some functional groups are always present
in between the carbon chain. eg.
Certain functional groups may be present
either at the end or in between the carbonchain. eg. – OH,
Enrich Your Knowledge
O
– C –
– C = C –, – C C –
O
– C – H,
O
– C – OH
6
Class X: Science
6
vi. Indicate the position of the functional group or side branch on the carbon chain by assigning it the lowest possible numerical prefix.
Few examples:
i. Name of carbon chain: Ethane Prefix/Suffix: Prefix Bromo Name: Bromo + ethane Bromoethane
ii. Name of carbon chain: Ethane Prefix/Suffix: Suffix ol Name: Ethane + ol Ethanol
iii. Name of carbon chain: Propane Prefix/Suffix: Suffix oic acid Name: Propane + oic acid
Propanoic acidiv.
Name of carbon chain: Propane Prefix/Suffix: Suffix yne Name: Propane + yne Propyne
v. Name of carbon chain: Propane Prefix/Suffix: Suffix ol Numerical prefix 2 Name: Propane + 2-ol Propan-2-ol
vi. Name of carbon chain: Butane Prefix/Suffix: Suffix ene Numerical prefix 2 Name: Butane + 2-ene But-2-ene
4.3 Chemical properties of carbon compounds Combustion: i. Combustion involves heating or burning of a
substance strongly in presence of air or oxygen.
ii. Carbon (all allotropic forms) burn in air or oxygen to form carbon dioxide (CO2) along with the release of a large amount of heat and light.
iii. Most carbon compounds also burn in air or
oxygen to form carbon dioxide (CO2) and water vapour (H2O) along with the release of a large amount of heat and light.
eg. iv. Combustion reaction is an oxidation reaction
since carbon is oxidised to CO2. v. Saturated hydrocarbons give a clean flame
(oxidising flame) on burning but when unsaturated hydrocarbons burn, they give a yellow flame (reducing flame) with lots of black smoke.
vi. The carbon content of unsaturated hydrocarbons is more than the hydrogen content and hence, the carbon is not completely burnt (i.e., it undergoes incomplete combustion). The unburnt carbon forms the black smoke and deposits as soot.
H – C – C – Br
H H
H H
2 1
H – C – C – OH
H H
H H
2 1
H – C – C – C – OH
H H
H H
3 2 1O
H – C – C CH
H
H
2 1 3
H – C – C = C – C – H
H
H
4 3 2
H
1
H H H
H – C – C – C – H
H H
H OH
3 2 1 H
H
+ Heat and light
CH4 + 2O2 CO2 + 2H2OMethane Oxygen Carbon
dioxide Watervapour
Enrich Your Knowledge
Alkyl groups: The removal of one hydrogen atom from an
alkane molecule gives an alkyl group. Their names are derived by replacing the final ‘ane’ in the name of the carbon chain by ‘yl’.
Alkane + yl Alkyl eg. The –CH3 group derived from methane is
named: Methyl group Carbon compounds having an alkyl group as
a side branch are named by using the prefix ‘alkyl’ along with the number indicating its position.
eg. Isobutane having CH3 group on the second carbon atom is named as 2-methylpropane.
CH3CH2OH + 3O2 2CO2 + 3H2O Ethanol Oxygen Carbon
dioxideWatervapour
+ Heat and light
C + O2 CO2 + Heat and lightCarbon Oxygen Carbon
dioxide
7
Chapter 04: Carbon and its Compounds
vii. If very limited air or oxygen is supplied, then it results in incomplete combustion of even saturated hydrocarbons giving yellow, sooty flame.
Oxidation: i. Addition of oxygen to any substance is called
oxidation. ii. The substances which are capable of adding
oxygen to other substances are called oxidising agents.
iii. Combustion is considered as complete oxidation. Carbon compounds also undergo partial oxidation in presence of certain oxidising agents.
eg. Oxidation of alcohols to carboxylic acids:
Here, alkaline potassium permanganate
(KMnO4) or acidified potassium dichromate (K2Cr2O7) act as oxidising agents.
Addition reaction: i. The reaction in which two or more molecules
react to form a single product is known as an addition reaction.
ii. This type of reaction occurs in unsaturated compounds having double or triple bonds.
eg. Hydrogenation: Addition of hydrogen (H2) to an unsaturated carbon compound in the presence of a catalyst such as nickel (Ni) or palladium (Pd) to give a saturated carbon compound is known as hydrogenation.
This process is commonly used in the
conversion of vegetable oils to fats (vanaspati ghee). This is done to slow down the process of rancidification of vegetable oils.
Substitution reaction: The reaction in which replacement of an atom
or a group of atoms in a molecule by another atom or group of atoms takes place is known as a substitution reaction.
eg. Chlorination of alkanes: When chlorine reacts with methane in
presence of sunlight or UV light, chlorine replaces the hydrogen atom to form chloromethane (CH3Cl).
On further reaction, chlorine replaces the
remaining hydrogen atoms one by one to give a mixture of different compounds.
i. ii. iii. 4.4 Some important carbon compounds –
Ethanol and ethanoic acid Ethanol: i. Molecular formula: C2H5OH ii. Molecular mass = 46 u iii. Structural formula: iv. Functional group present: Alcohol v. Common name: Ethyl alcohol
CH3CH2OH Ethanol
(Ethyl alcohol)
CH3COOH Alkaline KMnO4 + Heat
OR Acidified K2Cr2O7 + Heat Ethanoic acid(Acetic acid)
H C = C H + H H Nickel473 K
H C C H
H H
H H
Ethene EthaneHH
Hydrogen
H C C O H
H
H
H
H
Enrich Your Knowledge
Baeyer’s test: Dilute alkaline KMnO4 is an oxidising agent
and is known as Baeyer’s reagent. This reagentoxidises alkenes in the presence of water toform an addition product. The purple colour ofdilute KMnO4 disappears. This decolourisationof KMnO4 solution is used to identify thepresence of double bond in alkenes.
MethaneCH4 + Cl2
sunlight or UV CH3Cl + HClChloromethane
+ HCl
Chloromethane
CH3Cl + Cl2 sunlight or UV CH2Cl2
Dichloromethane
+ HCl
Dichloromethane
CH2Cl2 + Cl2sunlight or UV CHCl3
Chloroform (Trichloromethane)
+ HCl
Chloroform (Trichloromethane)
CHCl3 + Cl2 sunlight or UV CCl4
Carbon tetrachloride
(Tetrachloromethane)
Enrich Your Knowledge
Bromine water test: When an alkene or alkyne is treated with
bromine (Br2) dissolved in carbon tetrachloride(CCl4), the reddish brown colour of brominedisappears since a colourless addition productis formed.
This decolourisation of bromine is used todetect the presence of C = C or C C bonds(i.e., presence of unsaturation).
8
Class X: Science
8
Properties of ethanol: i. Ethanol is a colourless liquid at room
temperature. ii. It has a pleasant odour. iii. Melting point = 156 K iv. Boiling point = 351 K v. Miscible in water in all proportions. Effect of ethanol on health: Ethanol is the active ingredient in alcoholic
drinks. If small quantity of dilute ethanol is consumed, it causes drunkenness. However, intake of even a small quantity of pure ethanol (i.e., absolute alcohol) can be lethal.
Reactions of ethanol: i. Reaction with sodium (Na) metal: When ethanol reacts with sodium metal, it
forms sodium ethoxide and hydrogen gas. ii. Reaction with concentrated sulphuric acid
(H2SO4): When ethanol is heated at 443 K with excess
of concentrated sulphuric acid, it forms ethene and water.
This reaction involves removal of a molecule
of water from ethanol and hence, the reaction is called dehydration reaction. The concentrated H2SO4 acts as the dehydrating agent which removes water from ethanol.
Uses of ethanol: i. It is the active ingredient of alcoholic drinks. ii. It is used as an industrial solvent. iii. It is used in medicines such as tincture iodine,
cough syrups, tonics, etc. iv. It is used as an additive in petrol. Ethanoic acid: i. Molecular formula: CH3COOH ii. Molecular mass = 60 u iii. Structural formula: iv. Functional group present: Carboxylic acid v. Common name: Acetic acid Properties of ethanoic acid: i. Ethanoic acid is a colourless, corrosive liquid
at room temperature. ii. It has a pungent smell at ordinary temperature.
iii. Melting point = 290 K. Below 290 K, it solidifies to an ice like mass called glacial acetic acid.
iv. Boiling point = 391 K v. Miscible in water in all proportions. 5-8 %
solution of ethanoic acid in water is known as vinegar. It is used as a preservative in pickles.
Acidic nature of ethanoic acid: i. Ethanoic acid has COOH functional group
and belongs to group of organic compounds called carboxylic acids.
ii. Carboxylic acids like ethanoic acid are weak acids as compared to mineral acids like HCl, H2SO4, etc. This is because carboxylic acids do not ionise completely in aqueous solution while mineral acids ionise completely in aqueous solution.
Reactions of ethanoic acid: i. Reaction with alcohols: Carboxylic acids react
with alcohols to form esters, which have sweet smell. When ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid as a catalyst, an ester (named as ethyl ethanoate, also called as ethyl acetate) and water are formed.
This reaction between a carboxylic acid and an
alcohol to form an ester is called esterification reaction.
When an ester is heated with dilute sodium hydroxide (an alkali) solution, it gets converted back into the original alcohol and sodium salt of the original carboxylic acid.
eg. This reaction is known as saponification since
it is used in the preparation of soap.
Ethyl ethanoateCH3 C O CH2 CH3 + NaOH
O
Sodium hydroxide
CH3 CH2 OH + CH3 C ONa
O
Ethanol Sodium ethanoate
Heat
CH3 C OH + CH3 CH2 O H
O
Ethanol
Conc. H2SO4 / Heat
CH3 C O CH2 CH3 + H2OWater
O
Ethyl ethanoate(Ester)
Ethanoic acid
H C C O H
H
OH
CH3CH2OH 2 4conc.H SO
443 K CH2 = CH2 + H2O
Ethanol Ethene Water
Hydrogengas
2C2H5OH + 2Na 2C2H5ONa + H2Ethanol Sodium Sodium
ethoxide
+
9
Chapter 04: Carbon and its Compounds
ii. Reaction with alkalis or bases: Ethanoic acid reacts with an alkali like sodium
hydroxide to give salt (sodium ethanoate or sodium acetate) and water.
iii. Reaction with carbonates and
hydrogencarbonates: Ethanoic acid reacts with carbonates and
hydrogencarbonates to form salt (sodium ethanoate or sodium acetate), carbon dioxide and water.
4.5 Soaps and detergents Soaps: i. Soaps are sodium or potassium salts of long
chain carboxylic acids (fatty acids).
ii. The two ends of a soap molecule have different properties. The ionic-end of soap dissolves in water (i.e., it is hydrophilic) while the hydrocarbon ‘tail’ of soap is insoluble in water (i.e., it is hydrophobic).
iii. When soap is at the surface of water, the soap
molecules will align along the surface of water with the ionic ends in water and the hydrocarbon tails protruding out of water.
iv. Inside water, the soap molecules form clusters
in which the hydrophobic ends are in the interior of the cluster while the hydrophilic ends are on the surface of the cluster. Such a spherical formation is called a micelle.
v. This micelle formation is responsible for the
cleansing action of soaps. vi. The hydrophobic end of the soap molecule
dissolves in oily dirt adhering to the cloth while the hydrophilic end dissolves in surrounding water. When the water is agitated, the oily dirt tends to lift off from the surface of the cloth into the water. Now, the soap micelles will completely encapsulate the oily dirt at their centres. These micelles form an emulsion in water and will not precipitate out due to the ion-ion repulsions. Thus, the dirt remains suspended and can be easily rinsed off.
Ethanoic acid CH3 C OH + NaOH CH3 C ONa
O O
Sodium hydroxide
Sodiumethanoate
+ H2OWater
+ CO2 + H2OWaterCarbon
dioxide
Ethanoic acid
CH3 C OH + NaHCO3 CH3 C ONa
O O
Sodium hydrogencarbonate
Sodiumethanoate
+ CO2 + H2OWaterCarbon
dioxide
Ethanoic acid 2CH3 C OH + Na2CO3 2CH3 C ONa
O O
Sodiumcarbonate
Sodiumethanoate
Na +Hydro-phobic
end
Hydrophilic end
Soap molecule
Hydrophobic tail
Water
Soap molecules on the surface of water
Hydrophilic head
Na+
Na+
Na+
Na+
Na+
Na+
Na+ Na+ Na+
Na+
Na+
Na+
Na+
Na+
Na+ Na+
Micelle formation by soapmolecules in water
Enrich Your Knowledge
Hydrolysis of esters: Esters can be converted to carboxylic acids (or
salts) and alcohols in the presence of an acid or an alkali.
In presence of an acid: Ester + H2O
dilute HClHeat
Carboxylic acid + Alcohol This reaction is known as acid hydrolysis of
an ester. In presence of an alkali: This reaction is known as alkaline hydrolysis
of an ester (or saponification).
Ester + NaOH Heat + Alcohol
Sodium salt of carboxylic acid
10
Class X: Science
10
Hard and soft water: i. The water that produces lather (foam) with
soap readily is called soft water. ii. The water that does not produce lather (foam)
with soap readily is called hard water. iii. The presence of calcium and magnesium salts
in water results in hardness of water. iv. Soaps react with calcium and magnesium ions
in the hard water to form insoluble substance called scum. As a result, more amount of soap is required for cleaning. Hence, soaps are not much effective in hard water.
Detergents: i. Detergents are ammonium, sulphate or
sulphonate salts of long chain hydrocarbons. ii. They are used to make shampoos and other
products used for cleaning clothes. Advantages of detergents over soaps: i. Detergents can be used in soft as well as hard
water. ii. Detergents are more soluble in water than
soaps. iii. Detergents have higher cleansing power than
soaps. iv. Detergents are generally non-biodegradable
while soaps are biodegradable. Multiple Choice Questions NCERT Exemplar MCQs 1. Carbon exists in the atmosphere in the form of
_______. (A) carbon monoxide only (B) carbon monoxide in traces and carbon
dioxide (C) carbon dioxide only (D) coal 2. Which of the following statements are usually
correct for carbon compounds? These _______.
(i) are good conductors of electricity (ii) are poor conductors of electricity (iii) have strong forces of attraction between
their molecules (iv) do not have strong forces of attraction
between their molecules (A) (i) and (iii) (B) (ii) and (iii) (C) (i) and (iv) (D) (ii) and (iv) 3. A molecule of ammonia (NH3) has _______. (A) only single bonds (B) only double bonds (C) only triple bonds (D) two double bonds and one single bond
4. Buckminsterfullerene is an allotropic form of _______.
(A) phosphorus (B) sulphur (C) carbon (D) tin 5. Which of the following are correct structural
isomers of butane? (i) (ii) (iii) (iv) (A) (i) and (iii) (B) (ii) and (iv) (C) (i) and (ii) (D) (iii) and (iv) Hint: Structural isomers are compounds having the
same molecular formula but different structures. The molecular formula of butane is C4H10. Structure (i) and (ii) have same molecular formula C4H10, only the structures are different. Hence, they are structural isomers of butane. Structure (iii) and (iv) have molecular formula C4H8 and hence, they are not structural isomers of butane.
6. 4Alkaline KMnO + Heat
3 2 3CH CH OH CH COOH
In the above given reaction, alkaline KMnO4 acts as _______.
(A) reducing agent (B) oxidising agent (C) catalyst (D) dehydrating agent 7. Oils on treating with hydrogen in the presence
of palladium or nickel catalyst form fats. This is an example of _______.
(A) addition reaction (B) substitution reaction (C) displacement reaction (D) oxidation reaction
H C C C C H
H
H
H
H
H
H
H
H
H C C C H
H
H
H
H C H
H
H
H
H C C H
H
H
H
H
H C C H
H C C C H
H
H
H H
C H
H
11
Chapter 04: Carbon and its Compounds
8. In which of the following compounds, — OH is the functional group?
(A) Butanone (B) Butanol (C) Butanoic acid (D) Butanal Hint: (A) (B) (C) (D) 9. The soap molecule has a _______. (A) hydrophilic head and a hydrophobic
tail (B) hydrophobic head and a hydrophilic tail (C) hydrophobic head and a hydrophobic
tail (D) hydrophilic head and a hydrophilic tail 10. Which of the following is the correct
representation of electron dot structure of nitrogen?
(i) (ii) (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv) 11. Structural formula of ethyne is _______. (i) H – C ≡ C – H (ii) H3C – C ≡ C – H (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv)
12. Identify the unsaturated compounds from the following:
(i) Propane (ii) Propene (iii) Propyne (iv) Chloropropane (A) (i) and (ii) (B) (ii) and (iv) (C) (iii) and (iv) (D) (ii) and (iii) Hint: Unsaturated compounds have double or triple
bonds between the carbon atoms. Among the given options, propene and
propyne have double and triple bonds respectively. Hence, these are unsaturated compounds.
13. Chlorine reacts with saturated hydrocarbons at
room temperature in the _______. (A) absence of sunlight (B) presence of sunlight (C) presence of water (D) presence of hydrochloric acid 14. In the soap micelles, _______. (A) the ionic end of soap is on the surface
of the cluster while the carbon chain is in the interior of the cluster
(B) the ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster
(C) both ionic end and carbon chain are in the interior of the cluster
(D) both ionic end and carbon chain are on the exterior of the cluster
15. Pentane has the molecular formula C5H12. It
has __________. (A) 5 covalent bonds (B) 12 covalent bonds (C) 16 covalent bonds (D) 17 covalent bonds Hint: The structural formula of pentane is Number of C C covalent bonds = 4 Number of C H covalent bonds = 12 Total number of covalent bonds = 16
C = C H
H
H
H C C
H
H
H
HHH
N N
N N
H C C C H
H
H
H
H
H
HPropane
H C C = C H
H
H
H H
Propene
H C C C H
H
HPropyne
H C C C Cl
H
H
H
H
H
HChloropropane
N N
H C C C C C H
H H H H
H
H
H H H H
N N
H C C
H H
H
H
H H
O C C H
Butanone Functional group is (Ketone) C
O
H C C C C
H
H
H
H
H
H
H
H
OH
Butanol
Functional group is OH (Alcohol)
H C C C
H H
H
H
HH
O C H
ButanalFunctional group is CHO (Aldehyde)
H C C C
H H
H
H
H H Butanoic acid
Functional group is COOH (Carboxylic acid)
O C OH
12
Class X: Science
12
16. Structural formula of benzene is _______. (i) (ii) (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv) 17. Ethanol reacts with sodium and forms two
products. These are _______. (A) sodium ethanoate and hydrogen (B) sodium ethanoate and oxygen (C) sodium ethoxide and hydrogen (D) sodium ethoxide and oxygen Hint: When ethanol reacts with sodium metal, it
forms sodium ethoxide and hydrogen gas. 18. The correct structural formula of butanoic acid
is _______. (i) (ii) (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv) 19. Vinegar is a solution of _______. (A) 50% – 60% acetic acid in alcohol (B) 5% – 8% acetic acid in alcohol (C) 5% – 8% acetic acid in water (D) 50% – 60% acetic acid in water
20. Mineral acids are stronger acids than carboxylic acids because _______.
(i) mineral acids are completely ionised (ii) carboxylic acids are completely ionised (iii) mineral acids are partially ionised (iv) carboxylic acids are partially ionised (A) (i) and (iv) (B) (ii) and (iii) (C) (i) and (ii) (D) (iii) and (iv) 21. Carbon forms four covalent bonds by sharing
its four valence electrons with four univalent atoms, eg. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of _______.
(A) helium (B) neon (C) argon (D) krypton Hint: Atomic number of carbon = 6 Electronic configuration of carbon = 2, 4 When carbon forms four covalent bonds by
sharing its valence electrons with four univalent atoms (eg. Hydrogen), it achieves stable electronic configuration of nearest noble gas, neon (2,8).
22. The correct electron dot structure of a water
molecule is _______. (i) (ii) (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv) 23. Which of the following is not a straight chain
hydrocarbon? (i) (ii) (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv) Hint: In structures (i), (ii) and (iii), all the carbon
atoms are attached by covalent bonds in a continuous straight chain.
(i) (ii)
C
H
C
C C
C
C
H
H
H H
H
H H
HH
HH
H
C
H
H H C
C C
C
C
H
H
H C C = C C OH
H H H O
H
H C C C C C OH
H H H O
H
H
H H H H
H C C C C OH
H H H
H
H
H H H
H C C C C OH
H H H O
H H H
H3C CH2 CH2 CH2 CH2 CH3
H3C CH2 CH2 CH2 CH2
CH3
H2C H2C H2C CH2
CH3
CH3
H H O
H H O
H H O
H H O
2C2H5OH + 2Na 2C2H5ONa + H2Ethanol Sodium Sodium
ethoxide Hydrogen
gas
H
C
H H H C
C C
C
C
H
H
CC
C C
C
C HH
HH
H
H
H
H
H3C CH2 CH2 CH2 CH2 CH3
61 2 3 4 5
H3C CH2 CH2 CH2 CH2
CH3
1 2 3 4 5
6
CH3CH CH2 CH2 CH3
H3C
13
Chapter 04: Carbon and its Compounds
(iii) In structure (iv), CH3 group is attached to
the second carbon atom of the chain forming a branch. Hence, compound in structure (iv) is a branched chain hydrocarbon.
(iv) 24. Which among the following are unsaturated
hydrocarbons? (i) H3C CH2 CH2 CH3 (ii) H3C C C CH3 (iii) (iv) (A) (i) and (iii) (B) (ii) and (iii) (C) (ii) and (iv) (D) (iii) and (iv) 25. Which of the following does not belong to the
same homologous series? (A) CH4 (B) C2H6 (C) C3H8 (D) C4H8
Hint: In homologous series, the consecutive members of the series differ from one another by CH2 group.
Methane (CH4) is the first member of homologous series of alkanes.
Second member is ethane (C2H6) Third member is propane (C3H8) Fourth member is butane (C4H10) Hence, C4H8 does not belong to the
homologous series of alkanes. 26. The name of the compound
CH3 CH2 CHO is _______. (A) Propanal (B) Propanone (C) Ethanol (D) Ethanal Hint: There are three carbon atoms in the chain. So,
the name of the basic carbon chain is ‘propane’. The functional group present in aldehyde ( CHO). So, the suffix used is ‘al’.
The name of the carbon chain is modified by replacing the final ‘e’ with ‘al’. So, the name of the given compound is ‘propanal’.
27. The heteroatoms present in CH3 CH2 O CH2 CH2Cl are _______. (i) oxygen (ii) carbon (iii) hydrogen (iv) chlorine (A) (i) and (ii) (B) (ii) and (iii) (C) (iii) and (iv) (D) (i) and (iv) 28. Which of the following represents
saponification reaction? (i) (ii) (iii) (iv) (A) (i) (B) (ii) (C) (iii) (D) (iv) 29. The first member of alkyne homologous series
is _______. (A) ethyne (B) ethene (C) propyne (D) methane Practical Based MCQs 1. Acetic acid is _______. [CBSE 2012] (A) soluble only in boiling water (B) soluble in water at room temperature (C) partially soluble in water (D) insoluble in water 2. On mixing acetic acid with water, _______.
[CBSE 2012] (A) a suspension is formed (B) a colloidal solution is formed (C) a homogeneous solution is formed (D) a heterogeneous solution is fomed 3. About 2 mL of acetic acid was taken in each
of the three test tubes P, Q and R and 5 mL, 10 mL and 15 mL of distilled water were added to them, respectively. Instantaneously, a clear solution is observed in the test tubes _______. [CBSE 2012]
(A) P and Q only (B) Q and R only (C) R and P only (D) P, Q and R 4. A student adds 2 mL of acetic acid to a test
tube containing 2 mL of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about 5 minutes, he observes that in the test tube there is _______.
[CBSE 2015] (A) a clear transparent colourless solution (B) a clear transparent pink solution (C) a precipitate settling at the bottom of the
test tube (D) a layer of water over the layer of acetic
acid
CH3COONa +NaOH CaO CH4 + Na2CO3
CH3COOH + C2H5OH 2 4H SOCH3COOC2H5
+ H2O
2CH3COOH + 2Na 2CH3COONa + H2
H3C CH CH3
CH3
CH3COOC2H5 +NaOH CH3COONa + C2H5OH
CH3 CH2 CHO
3 2 1
H3C C = CH2
CH3
H2C H2C H2C CH2
CH3
CH3 1
2 3 4 5
6
12 3 4 5CH CH2 CH2 CH3
CH3
H3C
14
Class X: Science
14
5. What do we observe on pouring acetic acid on red and blue litmus papers?
[CBSE 2015] (A) Red litmus remains red and blue
litmus turns red. (B) Red litmus turns blue and blue litmus
remains blue. (C) Red litmus turns blue and blue litmus
turns red. (D) Red litmus becomes colourless and blue
litmus remains blue. 6. In an experiment to study the properties of
ethanoic acid, a student takes about 3 mL of ethanoic acid in a dry test tube. He adds an equal amount of distilled water to it and shakes the test tube well. After some time, he is likely to observe that _______.
[CBSE 2014] (A) a colloid is formed in the test tube (B) the ethanoic acid dissolves readily in
water (C) the solution becomes light orange (D) water floats over the surface of ethanoic
acid 7. The odour of acetic acid resembles that of
_______. [CBSE 2012] (A) rose (B) burning plastic (C) vinegar (D) kerosene 8. A student takes about 2 mL ethanoic acid in a
dry test tube and adds a pinch of sodium hydrogen carbonate to it. He reports the following observations:
I. Immediately a colourless and odourless gas evolves with a brisk effervescence.
II. The gas turns lime water milky when passed through it.
III. The gas burns with an explosion when a burning splinter is brought near it.
IV. The gas extinguishes the burning splinter that is brought near it.
The correct observations are _______. [CBSE 2013, 2014]
(A) I, II and III (B) II, III and IV (C) III, IV and I (D) I, II and IV 9. A student adds a few drops of ethanoic acid to
test tubes X, Y and Z containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate, respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding ethanoic acid in each one of them, in which of the test tube or test tubes the flames will be extinguished? [CBSE 2014]
(A) X and Y (B) Y and Z (C) X and Z (D) only Z
10. Among the two test tubes I and II, one contains acetic acid and another contains water. Which of the properties of acetic acid can be used to identify acetic acid from it?
I. Colour change with universal indicator II. Reaction with NaHCO3 III. Colour of the solution IV. Transparent nature
[CBSE 2013] (A) I and II (B) II and III (C) III and IV (D) I and IV 11. Select the correct observation about dilute
solution of acetic acid. [CBSE 2013] (A) It smells like rotten egg and turns blue
litmus red. (B) It smells like vinegar and turns red
litmus blue. (C) It smells like rotten egg and turns red
litmus blue. (D) It smells like vinegar and turns blue
litmus red. 12. A student takes sodium hydrogen carbonate
powder in a test tube and pours 4-5 drops of acetic acid over it. He observes _______.
[CBSE 2013] (A) no reaction in the test tube (B) bubbles of a colourless and odourless
gas (C) a colourless gas with a pungent smell (D) evolution of brown coloured gas along
with a brisk effervescence in the test tube
13. Four students performed an experiment of
acetic acid with sodium carbonate (I), sodium hydroxide (II), sodium bicarbonate (III) and sodium chloride (IV) separately. Each one brought burning candle near the mouth of the test tube. The candle would not be extinguished near the mouth of the test tubes:
(I) (II)
Sodium carbonate
Acetic acid
(I) (II)
Sodium hydroxide
Acetic acid
15
Chapter 04: Carbon and its Compounds
[CBSE 2012] (A) I and II (B) I and III (C) II and III (D) II and IV 14. Which of the following statements is not
correct? [CBSE 2012] (A) Acetic acid is a weak acid and it ionizes
only partially. (B) Acetic acid turns red litmus blue but
it does not affect blue litmus. (C) Acetic acid is highly soluble in water. (D) Acetic acid reacts with sodium
hydrogencarbonate to form a colourless and odourless gas.
15. Ethanoic acid was added to washing soda solution and the gas evolved was tested with a burning splinter. Which of the following four observations is correct? [CBSE 2012]
(A) The gas burns with a pop sound and the flame gets extinguished.
(B) The gas does not burn but the splinter burns with a pop sound.
(C) The flame extinguishes and the gas does not burn.
(D) The gas burns with a blue flame and the splinter burns brightly.
16. Deepa was asked to identify bottles of acetic acid from a shelf where a number of other labelled bottles were placed. She reads the labels as:
(i) Vinegar (ii) Formic acid (iii) Ethanoic acid (iv) Ethanol Correct identification would be _______.
[CBSE 2012] (A) i, ii (B) i, iv (C) ii, iv (D) i, iii 17. Manoj was asked to list the properties of
acetic acid after he had studied them in the laboratory. According to him acetic acid:
(i) is insoluble in water (ii) turns blue litmus paper red (iii) reacts with Na2CO3 to form NaOH and
CO2
(iv) has sweet smell like perfume The correct property out of the above
mentioned properties is _______. [CBSE 2012]
(A) i (B) ii (C) iii (D) iv
18. Acetic acid was added to a solid ‘X’ kept in a test tube. A colourless, odourless gas ‘Y’ was evolved. The gas was passed through lime water which turned milky. It was concluded that _______. [CBSE 2012]
(A) Solid X is NaOH, Y is CO2 (B) X is NaHCO3, Y is CO2 (C) X is CH3COONa, Y is CO2 (D) X is NaHCO3, Y is SO2 19. Soaps are prepared by the alkaline hydrolysis
of _______. [CBSE 2016] (A) salts (B) carboxylic acids (C) esters (D) alcohols 20. Which of the following sets of materials can
be used for conducting a saponification reaction for the preparation of soap?
[CBSE 2016] (A) Ca(OH)2 and neem oil (B) NaOH and neem oil (C) NaOH and mineral oil (D) Ca(OH)2 and mineral oil 21. We need 20% aqueous solution of sodium
hydroxide for the study of saponification reaction. When we open the lid of the bottle containing solid sodium hydroxide we observe it in which form? [CBSE 2014]
(A) Colourless transparent beads (B) Small white beads (C) White pellets/flakes (D) Fine white powder 22. During saponification reaction, Rupal takes
refined oil in test tube and adds 20% NaOH solution. She then stirs the reacting mixture and observes that soap formed _______.
[CBSE 2015] (A) floats over the resulting solution in the
test tube (B) settles down in the test tube (C) gets dispersed in the resulting mixture in
the test tube (D) dissolves in the resulting mixture in the
test tube 23. While studying saponification reaction for the
preparation of soap, a teacher suggested to a student to add a small quantity of common salt to the reaction mixture. The function of common salt in this reaction is to _______.
[CBSE 2014] (A) reduce the alkalinity of the soap (B) reduce the acidity of the soap (C) enhance the cleansing capacity of soap (D) favour precipitation of soap
(III)
Sodium bicarbonate
Acetic acid
(IV)
Sodium chloride
Acetic acid
16
Class X: Science
16
24. Rupal performs saponification reaction in the chemistry laboratory. She takes vegetable oil and alkali and heats it. Soap starts precipitating but it does not precipitate completely. The solution which facilitates precipitation of soap could be __________.
[CBSE 2016] (A) hydrochloric acid (B) acetic acid (C) sodium chloride (D) calcium chloride 25. While studying saponification reaction, a
student measures the temperature of the reaction mixture and also finds its nature using blue/red litmus paper. On the basis of his observations, the correct conclusion would be _______. [CBSE 2014]
(A) the reaction is exothermic and the reaction mixture is acidic
(B) the reaction is endothermic and the reaction mixture is acidic
(C) the reaction is endothermic and the reaction mixture is basic
(D) the reaction is exothermic and the reaction mixture is basic
26. Read the following statements: I. When a red litmus paper is dipped into
reaction mixture of a saponification reaction, it turns blue and the reaction is exothermic.
II. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is exothermic.
III. When a red litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic.
IV. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic.
Which of the above statements are correct? [CBSE 2015]
(A) I and II (B) II and III (C) III and IV (D) I and IV 27. Consider the following comments about
saponification reactions: I. Heat is evolved in these reactions. II. For quick precipitation of soap, sodium
chloride is added to the reaction mixture.
III. Saponification reactions are a special kind of neutralization reactions.
IV. Soaps are basic salts of long chain fatty acids.
The correct comments are __________. [CBSE 2016]
(A) I, II and III (B) II, III and IV (C) I, II and IV (D) only I and IV 28. The chemicals used for the preparation of
toilet soap are _______. [CBSE 2015] (A) fat and sodium hydroxide (B) fat and potassium hydroxide (C) water and sodium hydroxide (D) water and potassium hydroxide Hint: Toilet soaps used for washing purposes are
sodium soaps. Soaps used in shampoos, shaving creams and bathing soaps are potassium soaps. Potassium soaps are softer than sodium soaps.
29. The cleansing action of soap is more in soft
water as it _______. [CBSE 2015] (A) is free from microbes (B) does not have salts in it (C) has impurities (D) has dissolved salts 30. Name of the salt from the following which
makes the water hard is _______. [CBSE 2016]
(A) calcium hydrogencarbonate (B) potassium chloride (C) sodium carbonate (D) sodium bicarbonate 31. In a locality, hard water, required for an
experiment, is not available. However, the following salts are available in the school laboratory:
1. Sodium sulphate 2. Calcium sulphate 3. Magnesium chloride 4. Sodium chloride 5. Calcium chloride 6. Potassium sulphate Which of the above salts may be dissolved in
water to obtain hard water for the experiment? [CBSE 2014]
(A) 2, 3 and 5 (B) 1, 2 and 5 (C) 1, 2, 4 and 6 (D) 3 and 5 only. 32. A student takes about 6 mL of distilled water
in each of the four test tubes P, Q, R and S. He then dissolves an equal amount of four different salts namely, sodium chloride in ‘P’, potassium chloride in ‘Q’, calcium chloride in ‘R’ and magnesium chloride in ‘S’. Next, he then adds 10 drops of soap solution to each test tube and shakes its contents. The test tubes in which scum (insoluble substance) is formed with soap are _______. [CBSE 2014]
(A) P and Q (B) Q and R (C) R and S (D) Q and S
17
Chapter 04: Carbon and its Compounds
33. Geeta took three water samples in test tubes A, B and C. She added soap solution to all the three test tubes. She observed lather in test-tube A and B and no lather in test-tube C. The correct conclusion is ______.
(A) C is soft water (B) B is hard water (C) A is hard water (D) Both A and B are soft water 34. A student takes four test tubes marked P, Q, R
and S of 25 mL capacity and fills 10 mL of distilled water in each. He dissolves one spoonfull of four different salts in each as: KCl in P, NaCl in Q, CaCl2 in R and MgCl2 in S. He then adds about 2 mL of a sample of soap solution to each of the above test tubes. On shaking the contents of each of the test tubes, he is likely to observe a good amount of lather (foam) in the test tubes marked _________. [CBSE 2016]
(A) P and Q (B) R and S (C) P, Q and R (D) P, Q and S Additional MCQs 1. In graphite, each carbon atom is bonded to
_______ other carbon atoms in the same plane. (A) two (B) three (C) four (D) six 2. Which of the following set of compounds have
the same molecular formula? (A) Propanone, propanoic acid (B) Propanal, propanone (C) Propanol, propanal (D) Propane, propene 3. An atom of nitrogen has _______ electrons in
its L shell. (A) three (B) four (C) five (D) six 4. A soap solution appears cloudy because
_______. (A) soap micelles absorb light (B) soap micelles precipitate out (C) soap molecules remain as it is and do
not form micelles (D) soap micelles scatter light NCERT Exercises 1. Ethane, with the molecular formula C2H6
has _______. (A) 6 covalent bonds (B) 7 covalent bonds (C) 8 covalent bonds (D) 9 covalent bonds Ans: (B)
2. Butanone is a four-carbon compound with the functional group _______.
(A) carboxylic acid (B) aldehyde (C) ketone (D) alcohol Ans: (C) 3. While cooking, if the bottom of the vessel is
getting blackened on the outside, it means that _______.
(A) the food is not cooked completely (B) the fuel is not burning completely (C) the fuel is wet (D) the fuel is burning completely Ans: (B) 4. Explain the nature of the covalent bond
using the bond formation in CH3Cl. Ans: i. Chloromethane (CH3Cl) molecule
contains three atoms of hydrogen (H), one atom of chlorine (Cl) and one atom of carbon (C).
ii. Hydrogen (Atomic number = 1) atom has electronic configuration (1) and it has one electron in its valence shell. It requires one more electron to attain the stable electronic configuration of its nearest noble gas i.e., helium (He).
iii. Chlorine (Atomic number = 17) atom has electronic configuration (2, 8, 7) and it has seven electrons in its valence shell. It requires one more electron to attain the stable electronic configuration of its nearest noble gas i.e., argon (Ar).
iv. Carbon (Atomic number = 6) atom has electronic configuration (2, 4) and it has four electrons in its valence shell. It requires four more electrons to attain the stable electronic configuration of its nearest noble gas i.e., neon (Ne).
v. Thus, in the formation of CH3Cl molecule, C-atom completes its octet by sharing its four electrons with three H-atoms and with one Cl-atom.
vi. Due to this sharing of electrons, all the atoms attain stable electronic configuration.
vii. Thus, CH3Cl contains three C – H and one C – Cl single covalent bond.
CH3Cl molecule
OR
H C Cl
H
H
H C Cl
H
H
18
Class X: Science
18
5. Draw the electron dot structures for: i. ethanoic acid ii. H2S iii. propanone iv. F2
Ans: i. Ethanoic acid (CH3COOH) ii. H2S iii. Propanone iv. F2 6. What is an homologous series? Explain
with an example. Ans: i. A series of carbon compounds having
the same functional group, similar chemical properties and the successive members differing from each other in their molecular formula by a CH2 (methylene) unit is called homologous series.
ii. Homologous series of alkanes: All alkanes have same general formula CnH2n+2 (where n = 1, 2, 3, ....) and they show similar chemical properties. The first member of the series is methane (CH4). The next succeeding member of the series is ethane (C2H6) and it differs by a CH2 unit. The first five members of homologous series of alkanes are listed in the following table:
Value of ‘n’
Name of compound
Molecular formula
1 Methane CH4 2 Ethane C2H6 3 Propane C3H8 4 Butane C4H10 5 Pentane C5H12
7. How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Ans: i. Physical properties:
Property Ethanol Ethanoic acid
a. Smell Pleasant
smell Pungent smell
b. Melting point 156 K 290 K c. Boiling point 351 K 391 K
ii. Chemical properties:
Reaction Ethanol Ethanoic acida. Action of
litmus Ethanol has no action on either red litmus or blue litmus solution.
Ethanoic acid turns blue litmus solution to red.
b. Action of sodium carbonate or sodium hydrogen carbonate
Ethanol does not react with sodium carbonate or sodium hydrogen carbonate.
Ethanoic acid gives brisk effervescence with sodium carbonate or sodium hydrogen carbonate due to the evolution of carbon dioxide gas.
8. Why does micelle formation take place
when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?
Ans: i. A soap molecule has two ends having different properties. The ionic end of the molecule is hydrophilic and it dissolves in water, while the hydrocarbon ‘tail’ of the molecule is hydrophobic and it dissolve in hydrocarbons. (i.e., it is insoluble in water.)
ii. When soap is added to water, the soap molecules form clusters in which the hydrophobic ends are in the interior of the cluster while the hydrophilic ends are on the surface of the cluster. Such a spherical formation is called a micelle.
iii. Micelle formation does not occur in ethanol since soap is soluble in ethanol.
S H H
C C HH
H
H
O
O
F F
C C HH
H
H O
C
H
H
19
Chapter 04: Carbon and its Compounds
9. Why are carbon and its compounds used as fuels for most applications?
Ans: Carbon and its compounds on burning in air or oxygen release a large amount of heat and light. Hence, carbon and its compounds are used as fuels for most applications.
10. Explain the formation of scum when hard
water is treated with soap. Ans: i. Hard water contains calcium and
magnesium ions. ii. When hard water is treated with soap,
the soap molecules react with calcium and magnesium ions to form insoluble white precipitate of calcium and magnesium salts of long chain carboxylic acid (i.e., fatty acid). This precipitate is called scum.
11. What change will you observe if you test
soap with litmus paper (red and blue)? Ans: Soap is a salt of a strong base (NaOH or
KOH) and a weak acid (carboxylic acid). So, its aqueous solution is basic in nature.
Hence, an aqueous solution of soap will turn red litmus paper blue.
12. What is hydrogenation? What is its
industrial application? Ans: i. The addition of hydrogen to an
unsaturated hydrocarbon in the presence of a catalyst such as nickel or palladium to form a saturated hydrocarbon is called hydrogenation.
ii. Industrial application: Hydrogenation is used for preparing vegetable ghee (vanaspati) from vegetable oils, which have long unsaturated carbon chains.
13. Which of the following hydrocarbons
undergo addition reactions? C2H6, C3H8, C3H6, C2H2 and CH4
Ans: Unsaturated hydrocarbons (i.e., hydrocarbons having double or triple bonds) undergo addition reactions.
i. C2H6 (Ethane) is a saturated hydrocarbon. It does not undergo addition reactions.
ii. C3H8 (Propane) is a saturated hydrocarbon. It does not undergo addition reactions.
iii. C3H6 (Propene) is an unsaturated hydrocarbon. It undergoes addition reactions.
iv. C2H2 (Ethyne) is an unsaturated hydrocarbon. It undergoes addition reactions.
v. CH4 (Methane) is a saturated hydrocarbon. It does not undergo addition reactions.
14. Give a test that can be used to differentiate
chemically between butter and cooking oil. OR
Give a chemical test to distinguish between butter and cooking oil. [CBSE 2011]
Ans: i. Butter generally has saturated carbon chains while cooking oil generally has unsaturated carbon chains.
ii. Unsaturated hydrocarbons undergo hydrogenation (i.e., addition of H2) in presence of a catalyst such as nickel or palladium.
iii. Thus, cooking oil can be hydrogenated to form fats (vanaspati ghee) while butter cannot be hydrogenated.
Note: The presence of unsaturation (in
cooking oil) can be detected using bromine water test.
15. Explain the mechanism of the cleaning
action of soaps. Ans: Cleansing action of soaps: i. Soap molecules are sodium or
potassium salt of long chain carboxylic acids (fatty acids).
ii. The two ends of a soap molecule have different properties. The ionic end of the molecule is hydrophilic and it dissolves in water, while the hydrocarbon ‘tail’ of the molecule is hydrophobic and it dissolves in hydrocarbons (i.e., it is insoluble in water).
R C C R
H
R
H
R
C = C R
R
R
R
Nickel catalyst2 Heat
H
Vegetable oil (Liquid state)
Vegetable Ghee(Solid state)
R C C R
H
R
H
R
C = C R
R
R
R
Nickel catalyst2 Heat
H
Vegetable oil(Liquid state)
Vegetable Ghee(Solid state)
Sodium salt of
fatty acid[Soap]
Ca2+ Calcium
ion [From hard
water]
Calcium salt of
fatty acid[Scum]
Na+ Sodium
ion
+ +
Sodium salt of
fatty acid[Soap]
Mg2+ Magnesium
ion [From hard
water]
Magnesiumsalt of
fatty acid [Scum]
Na+ Sodium
ion
+ +
20
Class X: Science
20
iii. Inside water, the soap molecules form
clusters in which the hydrophobic ends are in the interior of the cluster while the hydrophilic ends are on the surface of the cluster. Such a spherical formation is called a micelle.
iv. The micelle formation is responsible for the cleansing action of soaps.
v. The hydrophobic end of the soap molecule dissolves in oily dirt adhering to the cloth while the hydrophilic end dissolves in surrounding water. When the water is agitated, the oily dirt tends to lift off from the surface of the cloth into the water. Now, the soap micelles will completely encapsulate the oily dirt at their centre.
vi. These micelles form an emulsion in
water and will not precipitate out due to the ion-ion repulsions. Thus, the dirt remains suspended and can be easily rinsed off.
NCERT Intext Questions 4.1 Bonding in carbon – The covalent bond 1. What would be the electron dot structure
of carbon dioxide which has the formula CO2?
Ans: i. Carbon dioxide (CO2) molecule contains two atoms of oxygen (O) and one atom of carbon (C).
ii. Oxygen (Atomic number = 8) atom has electronic configuration (2, 6) and it has six electrons in its valence shell. It requires two more electrons to attain the stable electronic configuration of its nearest noble gas i.e., neon (Ne).
iii. Carbon (Atomic number = 6) atom has electronic configuration (2, 4) and it has four electrons in its valence shell. It requires four more electrons to attain the stable electronic configuration of its nearest noble gas i.e., neon (Ne).
iv. Thus, in the formation of CO2 molecule, C-atom completes its octet by sharing two electrons with one O-atom and the remaining two electrons with the other O-atom.
v. Due to this sharing of electrons, O-atoms also complete their respective octets. There are two double bonds in CO2 molecule.
2. What would be the electron dot structure of
a molecule of sulphur which is made up of eight atoms of sulphur? (Hint: The eight atoms of sulphur are joined together in the form of a ring.)
Ans: i. Sulphur (atomic number = 16) has electronic configuration (2, 8, 6). It has six electrons in its valence shell.
ii. It requires two more electrons to attain the stable electronic configuration of its nearest noble gas i.e., argon (Ar).
iii. Each sulphur atom completes its octet by sharing two of its valence electrons with two separate sulphur atoms forming a eight-membered ring structure.
Carbon dioxide (CO2) molecule
OR O = C = OCO O
Micelle formation around an oil droplet
Na+
Na+
Na+
Na+
Na+
Na+ Na+
Na+ Na+
Na+
Na+
Na+
Na+
Na+ Na+
Na+
Oil droplet (dirt)
Na+Hydro-phobic
end Soap molecule
Hydrophilic end
S S
S S
S
S
S
S
(a)
OR
S
S
S S
S S
S S
(b) Sulphur (S8) molecule
21
Chapter 04: Carbon and its Compounds
4.2 Versatile nature of carbon 3. How many structural isomers can you draw
for pentane? Ans: The molecular formula of pentane is C5H12.
Three different carbon ‘skeletons’ are possible with five carbon atoms.
By filling the remaining valencies with
hydrogen atoms, three structural isomers can be drawn for pentane.
i. ii. iii. 4. What are the two properties of carbon
which lead to the huge number of carbon compounds we see around us?
Ans: The two properties of carbon which lead to the huge number of carbon compounds are:
i. Catenation: The unique property of carbon atom to form covalent bonds with other carbon atoms giving rise to large molecules is called catenation. Due to this property, straight chains, branched chains or rings of carbon atoms are formed. This results in huge number of carbon compounds having carbon atoms linked to each other.
ii. Tetravalency: Carbon has a valency of four (i.e., tetravalent). Hence, it can form bonds with four other atoms of carbon or atoms of other monovalent elements. Carbon, being small in size,
forms strong bonds with many elements such as hydrogen (H), oxygen (O), nitrogen (N), sulphur (S), chlorine (Cl), etc. In addition, carbon atom can form multiple bonds with itself and atoms of other elements. This increases the number of carbon compounds.
5. What will be the formula and electron dot
structure of cyclopentane? Ans: i. The molecular formula of cyclopentane
is C5H10. ii. Each carbon atom completes its octet by
sharing two of its valence electrons with two other carbon atoms and by sharing remaining two electrons with two hydrogen atoms.
Due to this sharing of electrons, each hydrogen atom also completes its duplet (i.e., 2 electrons in the outermost shell).
iii. This results in five-membered ring structure.
6. Draw the structures for the following
compounds: i. Ethanoic acid ii. Bromopentane iii. Butanone iv. Hexanal Are structural isomers possible for
bromopentane? Ans: i. ii.
C C C C C C C C C
C
C C C
C
C
H C C C C C H
H
H
H
H
H
H
H
H
H
H n-Pentane
Ethanoic acid(Acetic acid)
H C C OH
H
H
O
Bromopentane
H C C C C C Br
H
H
H
H
H
H
H
H
H
H
H C C C H
H
H
H
HH – C – H
H – C – H
H
HNeopentane
C
C
C C
C
H
H
H
H
H H
H
H
H
H
Electron dot structure of cyclopentane
Isopentane
H C C C C H
H
H
H
H
H
H
H
H H C H
22
Class X: Science
22
Yes, structural isomers are possible for bromopentane. The presence of bromine atom on different carbon atoms of the chain results in three structural isomers.
The other two isomers of bromopentane have bromine atom linked to second and third carbon atoms respectively.
iii. iv. 7. How would you name the following
compounds? i. ii. iii. Ans: i. The number of carbon atoms in the
chain is 2. So, the name of the carbon chain is ‘ethane’.
Bromine (Br) atom is the functional group present. So, the prefix used is ‘bromo’. Thus, the name of the given compound is Bromoethane.
ii. The number of carbon atoms is 1. So,
the name of the carbon chain is ‘methane’.
Aldehyde group is the functional group present. So, the suffix
used is ‘al’. The name of the carbon chain is modified by replacing the final ‘e’ with ‘al’.
Thus, the name of the given compound is Methanal.
iii. The number of carbon atoms in the
chain is 6. So, the name of the carbon chain is ‘hexane’. The triple bond between carbon atoms (i.e., alkyne) is the functional group present. So, the suffix used is ‘yne’. The name of the carbon chain is modified by replacing the final ‘e’ with ‘yne’.
Thus, the name of the given compound is Hexyne (or Hex-1-yne indicating the position of triple bond).
4.3 Chemical properties of carbon compounds 8. Why is the conversion of ethanol to
ethanoic acid an oxidation reaction? Ans: The conversion of ethanol to ethanoic acid
involves addition of oxygen. Hence, it is an oxidation reaction.
9. A mixture of oxygen and ethyne is burnt for
welding. Can you tell why a mixture of ethyne and air is not used?
Ans: i. Ethyne is an unsaturated hydrocarbon. On combustion in air, it produces a yellow flame with lots of black smoke.
ii. Due to this incomplete combustion, heat produced is low and temperature obtained is also low.
iii. For welding purposes, high temperature is required.
iv. When a mixture of ethyne and oxygen is used, complete combustion is achieved and very high temperature required for welding is obtained.
Hence, a mixture of ethyne and oxygen is used for welding instead of a mixture of ethyne and air.
CH3 CH2 Br H C = O
H
H C C C C H
H
H
H
H
O
H
H
Butanone
H C C C C C C H
H
H
H
H
O
H
H
Hexanal
H H
H H
CH3 CH2 Br2 1
H C = O
H
C H
O
H C C C C C C H
H H H
H
H
H H H
H C C C C C ≡ C H
H
H
H
H H
HH
H
6 5 4 3 2 1
H C C C C C H
H
H
H
H
H
H
H
Br
H
H
5 4 3 2 1
H C C C C C H
H
H
H
H
H
Br
H
H
H
H
5 4 3 2 1
CH3 C OH + H2O
O
Ethanoic acid Water
CH3 – CH2 – OH + 2[O] Alkaline KMnO Heat4orAcidifiedK Cr O Heat2 2 7
Ethanol Oxygen (From theoxidizing agent)
53
Chapter 04: Carbon and its Compounds
Formative Assessment
1. Brain teaser:
Solve the following crossword:
1.
2. 3.
4. 5.
6.
Across:
2. 5 - 8% solution of acetic acid in water. (7)
4. The metal used as a catalyst in the hydrogenation of vegetable oils. (6)
6. A cyclic carbon compound with molecular formula C6H6 having alternate carbon-carbon single and double bonds. (7)
Down:
1. The hetero atom present in butanoic acid. (6)
3. An alkane, which is a major component of bio-gas. (7)
5. The active ingredient of alcoholic beverages. (7) 2. Check your grasp:
Complete the following table. One is done for you!
Sr. No.
Molecular formula Saturated or Unsaturated
i. C3H6 Unsaturated
ii. C8H14
iii. C5H12
iv. C7H14
v. C5H8
vi. C8H16
vii. C2H6
viii. C9H18
54
Class X: Science
54
3. Identify the functional groups:
Given below are the structures of two compounds.
(A) Citric acid which is present in oranges and lemons.
(B) Glucose which is present in sweet fruits and is considered the most abundant organic compound on earth.
Write the names of the functional groups that are highlighted in these structures.
Answers to Formative Assessment 1.
1.O X Y
2.V I N E G A R 3.M E
E
4.N I C K 5.E L T
T H
H A
A N
6.B E N Z E N E
O
L 2. ii. Unsaturated iii. Saturated iv. Unsaturated v. Unsaturated vi. Unsaturated vii. Saturated viii. Unsaturated 3. 1. Carboxylic acid 2. Alcohol 3. Carboxylic acid 4. Aldehyde 5. Alcohol 6. Alcohol
H C OH
HO C H
H C OH
H C OH
4
5
6
H C OH
CH2 OH
Glucose
C H
O
CH2 C OH
O
HO C C OH
CH2 C OH
O
O
2
1
Citric acid
3
(A)
(B)
