Done 16-1-18 - Kopykitab

MBD

9

NCER

T S

OLU

TIONS s

cien

ce

P-276 GSM-52

Sp-9.3288 mmCMYK

SOLUTION

S

SCIENCE·

····

Complete and comprehensive summary in the beginning of each chapter

All NCERT textbook questions with answers

Simple language and attractive style

An invaluable book from examination point of view

Enriched with the experience of master minds

With NCERT Exemplar Problems

9

C M Y KDone 16-1-18

1801M0369C4361 An ISO 9001:2015 Certified Company

ISBN 9789387763364

9 789387 763364

SOLUTIONS

MBD

NCERT

SCIENCE 9

MALHOTRA BOOK DEPOT(Producers of Quality MBD Books)

An ISO 9001:2015 Certified Company

Price ` 95.00

Science-G09_FM.indd 1 1/6/2018 5:36:28 PM

OUR ADDRESSES IN INDIA New Delhi: New Delhi: MBD House, Gulab Bhawan, 6, Bahadur Shah Zafar Marg Ph. 23317931, 23318301 Mumbai: A-683, T.T.C. Industrial Area, M.I.D.C. Off. Thane-Belapur Road, Navi Mumbai

Ph. 32996410, 27780821, 8691053365 Chennai: No. 26 B/2 SIDCO Estate, North Phase, Pataravakkam Ambattur Industrial Estate, Ambattur

Ph. 26359376, 26242350 Chennai: Plot No. 3018, Old Y Block, 3rd Street, 12th Main Road, Anna Nagar West Ph. 23741471 Kolkata: Satyam Building, 46-D, Rafi Ahmed Kidwai Marg Ph. 22296863, 22161670 Jalandhar City: MBD House, Railway Road Ph. 2458388, 2459046, 2455663 Bengaluru: 124/31, 1st Main, Industrial Town (Near Chowdeshwari Kalyan Mantap), West of Chord Road,

Rajajinagar Ph. 23103329, 23104667 Hyderabad: 3-4-492, Varun Towers, Barkatpura Ph. 27564788, 9985820001 Ernakulam: Surabhi Building, South Janatha Road, Palarivattom Ph. 2338107, 2347371 Pune: Survey No. 44, Behind Matoshree Garden, Kondhwa–Khadi Machine, Pisoli Road, at Post-Pisoli

Ph. 65271413, 65275071 Nagpur: ‘Chandrakor’, Plot No. G-15, Aath Rasta Chowk, West High Court Road, Laxmi Nagar

Ph. 2248104, 2248106, 2248649, 2245648 Ahmedabad: Godown No.10, Vedant Prabha Estate, Opp. ONGC Pumping Station, Sarkhej Sanand Road,

Sarkhej Ph. 26890336, 7600024542 Cuttack: Badambadi, Link Road Ph. 2367277, 2367279, 2313013 Guwahati: Chancellor Commercial, Hem Baruah Road, Paan Bazar Ph. 2131476, 8822857385 Lucknow: 173/15, Dr. B. N. Verma Road, Old 30 Kutchery Road Ph. 4010992, 4010993 Patna: Ist Floor, Annapurna Complex, Naya Tola Ph. 2672732, 2686994, 2662472 Bhopal: Plot No. 137, 138, 139, Sector-I, Special Industrial Area, Govindpura Ph. 2581540, 2601535 Jabalpur: 840, Palash Chamber, Malviya Chowk Ph. 2405854 Goa: H. No. 932, Plot No. 66, Kranti Nagar (Behind Azad Bhawan), Alto Porvorim, Bardez

Ph. 2413982, 2414394 Jaipur: C-66A, In front of Malpani Hospital, Road No. 1, V.K. Industrial Area, Sikar Road

Ph. 4050309, 4020168 Raipur: Behind Aligarh Safe Steel Industries, Vidhan Sabha Road, Avanti Bai Chowk, Lodhi Para Pandri

Ph. 2445370, 4052529 Karnal: Plot No. 203, Sector-3, HSIDC, Near Namaste Chowk, Opp. New World Ph. 2220006, 2220009 Shimla (H.P.): C-89, Sector-I, New Shimla-9 Ph. 2670221, 2670816 Jammu (J&K): Guru Nanak College of Education, Jallo Chak, Bari Brahmana Ph. 2467376, 9419104035 Ranchi (Jharkhand): MBD House, Shivani Complex, 2nd Floor, Jyoti Sangam Lane, Upper Bazar

Ph. 7260813703, 7260813710 Sahibabad (U.P.): B-9 & 10, Site IV, Industrial Area Ph. 3100045, 2896939 Dehradun (Uttarakhand): Plot No. 37, Bhagirathipuram, Niranjanpur, GMS Road Ph. 2520360, 2107214DELHI LOCAL OFFICES: Delhi (Shakarpur): MB 161, Street No. 4 Ph. 22546557, 22518122 Delhi (Daryaganj): MBD House, 4587/15, Opp. Times of India Ph. 23245676 Delhi (Patparganj): Plot No. 225, Industrial Area Ph. 22149691, 22147073

We are committed to serve students with best of our knowledge and resources. We have taken utmost care and paid much attention while editing and printing this book but we would beg to state that Authors and Publishers should not be held responsible for unintentional mistakes that might have crept in. However, errors brought to our notice shall be gratefully acknowledged and attended to.

© All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permission of the publisher. Any breach will entail legal action and prosecution without further notice.

Published by : MALHOTRA BOOK DEPOT MBD House, Railway Road, Jalandhar City.

Printed at : M. GULAB SINGH & SONS (P) LTD. B-5/14, Site IV, Industrial Area, Sahibabad (U.P.)


CONTENTS

1 Matter in Our Surroundings 1 – 12

2 Is Matter Around us Pure 13 – 33

3 Atoms and Molecules 34 – 55

4 Structure of the Atom 56 – 75

5 The Fundamental Unit of Life 76 – 94

6 Tissues 95 – 113

7 Diversity in Living Organisms 114 – 133

8 Motion 134 – 153

9 Force and Laws of Motion 154 – 168

10 Gravitation 169 – 183

11 Work, Energy and Floatation 184 – 203

12 Sound 204 – 222

13 Why Do We Fall Ill? 223 – 234

14 Natural Resources 235 – 250

15 Improvement in Food Resources 251 – 270



CHAP

TER

1 Matter in Our Surroundings

CHAPTER AT A GLANCE� All matter is made up of a large number of extremely small particles.� There are vacant spaces between the particles of matter.� Particles of matter are continuously moving.� There is an attractive force between the particles of matter and the

strength of this force results in different states of matter.� There are three states of matter, solid, liquid and gas.� The forces of attraction between molecules are maximum in solids,

intermediate in liquids and minimum in gases.� The vacant spaces, between particles of matter are minimum in

solids, intermediate in liquids and maximum in case of gases.� Kinetic energies of particles are minimum in the case of solids,

intermediate in the case of liquids and maximum in the case of gases.

� The arrangement of particles is most ordered in case of solids. In case of liquids, the layers of particles can slip over each other. In case of gases, there is no order and particles are in a state of rapid random motion in all directions.

� The different states of matter are interconvertible.� The states of matter can be changed by interchanging temperature

or pressure or both.� The slow escape of the particles of a liquid from surface to the

vapour state is called evaporation.� The rate of evaporation depends upon the surface area exposed to

the atmosphere, temperature, humidity and wind speed.� Evaporation causes cooling. (Note: In addition to the three states of matter there are two

others states of matter i.e. Plasma, which exists at very high temperature and Bose-Einstein condensate which exists at very low temperature.)

NCERT IN-TEXT QUESTIONS

Page 31. Which of the following are matter? Chair, air, love, smell, hate, almonds, thought, cold, cold drink,

smell of perfume.Ans. Chair, air, almonds, cold drink and smell of perfume.

MBD_NCERT SOLUTIONS SCI_9 (E) Part-I.indd 1 1/6/2018 2:49:28 PM

MBD NCERT Solutions Science IX2

2. Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away,

but to get the smell from cold food you have to go close.Ans. This is because the rate of diffusion of a gas increases with the

increase in temperature. In hot food, the rate of diffusion is larger than that in cold food.

3. A diver is able to cut through water in a swimming pool, which property of matter does this observation show?

Ans. The diver is able to cut through water in a swimming pool because in water the attractive forces between the molecules are small.

4. What are the characteristics of the particles of matter?Ans. The characteristics of the particles of matter are: 1. The have vacant spaces between them. 2. The are always in motion. 3. There are attractive forces between particles of matter.

Page 61. The mass per unit volume of a substance is called density

(density = mass/volume). Arrange the following in order of increasing density:

air, exhaust from chimneys, honey, water, chalk, cotton and iron.Ans. The increasing order of density is: (air < exhaust from chimney < cotton < water < honey < chalk <

iron). 2. (a) Tabulate the differences in the characteristics of states

of matter. (b) Comment upon the following: rigidity, compressibility,fluidity,fillingagas container,

shape, kinetic energy and density.Ans. (a) Differences in the characteristics of states of matter:

Characteristics Solid Liquid Gas1. Vacant spaces Very small Small Very large2. Attractive forces

between particlesVery large Small Negligible

3. Compressibility Negligible Low High4. Rigidity High Low Non-rigid5. Density High Low Low


3Matter in Our Surroundings

6. Kinetic energy Small High as comparedto solid

Very high

(b) Rigidity. It is the property by virtue of which a substance can retain its shape when a force is applied to it. Solids possess the property of rigidity.

Compressibility. The property by virtue of which the volume of a substance can be decreased by applying force or pressure on it is known as compressibility. Gases have high compressibility because of large vacant spaces between the molecules of a gas.

Fluidity. It is the property by virtue of which the molecules of one substance can flow from one point to another. Liquids and gases possess fluidity.

Filling a gas container. A gas fills a container because there are negligible attractive forces between the molecules of a gas and the molecules move with very high velocities in all possible directions.

Shape. It is the definite geometrical arrangement of constituent particles of a substance. Solids have definite shapes.

Kinetic energy. It is the energy possessed by a particle due to its motion.

Density. Density of a substance is the mass per unit volume. Its units are g/cm3 or kg/m3.

3. Give reasons: (a) Agasfillscompletelythevesselinwhichitiskept. (b) A gas exerts pressure on the walls of the container. (c) A wooden table should be called a solid. (d) We can easily move our hand in air but to do the same in

solid block. we need a karate expert.Ans. (a) This is so because in a gas the attractive forces between the

particles are negligible and molecules of a gas move with very high speeds in all possible directions.

(b) This is due to the bombardment of the molecules of a gas against the walls of the container.

(c) This is because it has a definite mass, volume and shape. (d) This is because in air, the attractive forces between the particles

are negligible but in a solid like block of wood, there are large attractive forces between the constituent particles.



4. Liquids generally have lower density as compared to solids. But youmusthaveobservedthaticefloatsonwater.Findoutwhy?

Ans. Ice floats over water because ice has lower density than liquid water. This is because for a given mass, ice has larger volume than liquid water.

Page 91. Convert the following temperatures to celsius scale: (a) 300 K (b) 573 KAns. (a) 300 K = 300 – 273 = 27°C (b) 573 K = 573 – 273 = 300°C2. What is the physical state of water at: (a) 250°C (b) 100°C Ans. (a) Vapour (b) Vapour3. For any substance, why does the temperature remain constant

during the change of state?Ans. This is because the supplied heat is used to overcome the attractive

forces between the particles.4. Suggest a method to liquefy atmospheric gases.Ans. The atmospheric gases can be liquefied by cooling the gases under

high pressure.

Page 101. Why does a desert cooler cool better on a hot dry day?Ans. This is because on a hot dry day, the evaporation of water is faster

due to higher temperature and lower humidity.2. How does the water kept in an earthen pot (matka) become cool

during summer?Ans. This is because water can move out from the pores of earthen pot

(matka) and it evaporates. Due to evaporation, water in the earthern pot cools down.

3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Ans. This is because the particles of acetone or petrol or perfume (being low boiling liquids) gain energy from our palm and the surroundings and thus evaporate to cause cooling.

4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

Ans. Because a saucer provides more surface area than a cup for evaporation of the liquid. It causes more cooling effect.

5. What type of clothes should we wear in summer?Ans. We should wear light coloured cotton clothes in summer.



NCERT TEXTBOOK EXERCISES

1. Convert the following temperatures to the Celsius scale. (a) 293 K (b) 470 KAns. (a) 293 K = 293 – 273 = 20°C (b) 470 K = 470 – 273 = 197°C2. Convert the following temperatures to the Kelvin scale. (a) 25°C (b) 373°CAns. (a) 25°C = 25 + 273 = 298 K (b) 373°C = 373 + 273 = 646 K3. Give reason for the following observations. (a) Naphthalene balls disappear with time without leaving

any solid. (b) We can get the smell of perfume sitting several metres away.Ans. (a) This is because naphthalene sublimes i.e. it directly changes

into vapour without melting. (b) This is because the molecules of perfume are moving with

very high speed (diffusion) in all the directions. 4. Arrange the following substances in increasing order of forces

of attraction between the particles: water, sugar, oxygen.Ans. The increasing order of intermolecular forces of attraction is

oxygen < water < sugar. 5. What is the physical state of water at: (a) 25°C (b) 0°C (c) 100°CAns. (a) At 25°C, water is liquid. (b) At 0°C, water is solid (Ice). (c) At 100°C, water is vapour (steam). 6. Give two reasons to justify that: (a) water at room temperature is a liquid. (b) an iron almirah is a solid at room temperature.Ans. (a) At room temperature water is liquid because the attractive

forces between the molecules of water are small and can move from one point to another.

(b) An iron almirah is a solid because the particles are held together by strong intermolecular attractive forces and these particles are very close to each other.

7. Why is ice at 273 K more effective in cooling than water at the same temperature?

Ans. Ice at 273 K is more effective in cooling than water at the same temperature because in ice, the molecules have lower energy as compared to the particles in the liquid water at the same temperature (273 K) and require latent heat of fusion for melting.



8. What produces more severe burns, boiling water or steam?Ans. Steam produces severe burns as compared to boiling water. This

is because in steam the molecules have higher kinetic energy than in boiling water.

9. Name A, B, C, D, E and F in the following diagram showing change of its state.

F

E

A

D

B

C

GASLIQUIDSOLID

INCREASE HEAT ANDDECREASE PRESSURE

DECREASEINCREASE

HEAT ANDPRESSURE

Ans. A—Fusion B—Vaporisation C—Condensation D—Solidification E—Sublimation F—Sublimation

NCERT EXEMPLAR QUESTIONS

Multiple Choice Questions (MCQs)1. Which one of the following sets of phenomena would increase

on raising the temperature? (a) evaporation, compression of gases, solubility (b) evaporation, solubility, diffusion, compression of gases (c) evaporation, diffusion, expansion of gases (d) diffusion, evaporation, compression of gases2. Seema visited a Natural Gas Compressing Unit and found that

thegascanbeliquefiedunderspecificconditionsoftemperatureand pressure. While sharing her experience with friends she got confused. Help her identify the correct set of conditions for the liquefaction of gases.

(a) high temperature, high pressure (b) low temperature, low pressure (c) low temperature, high pressure (d) high temperature, low pressure3. Theproperty toflow isunique tofluids.Whichoneof the

following statements is correct? (a) only liquids behave like fluids (b) only gases behave like fluids (c) gases and liquids behave like fluids (d) gases and solids behave like fluids



4. During summer, water kept in an earthen pot becomes cool because of the phenomenon of

(a) osmosis (b) transpiration (c) diffusion (d) evaporation5. A few substances are arranged in the increasing order of ‘forces

of attraction’ between their particles. Which one of the following is a correct arrangement?

(a) salt, juice, air (b) water, air, wind (c) oxygen, water, sugar (d) air, sugar, oil6. On converting 25°C, 38°C and 66°C to Kelvin scale, the correct

sequence of temperature will be: (a) 298 K, 311 K and 339 K (b) 298 K, 310 K and 338 K (c) 273 K, 278 K and 543 K (d) 298 K, 300 K and 338 K7. Choose the correct statement of the following: (a) conversion of solid into liquid is called sublimation (b) conversion of vapours into solid without passing through the

liquid state is called sublimation (c) conversion of solid into vapours without passing through the

liquid state is called vaporisation (d) conversion of vapours into solid without passing through the

liquid state is called freezing8. The boiling points of diethyl ether, acetone and n-butyl

alcohol are 35°C, 56°C and 118°C respectively. Which one of the following correctly represents their boiling points in Kelvin scale?

(a) 329 K, 392 K, 308 K (b) 306 K, 329 K, 391 K (c) 308 K, 329 K, 391 K (d) 308 K, 329 K, 392 K9. Which condition out of the following will increase the evaporation

of water? (a) adding common salt to water (b) decrease in temperature of water (c) less exposed surface area of water (d) increase in temperature of water10. In which of the following conditions, the distance between the

molecules of hydrogen gas would increase? (i) adding more hydrogen gas to the container without increasing

the volume of the container.



(ii) increasing the volume of the container of hydrogen gas. (iii) some hydrogen gas leaking out of the container. (iv) increasing pressure on hydrogen contained in a closed container. (a) (i) and (iv) (b) (ii) and (iv) (c) (ii) and (iii) (d) (i) and (iii)

Ans. 1. (c) evaporation, diffusion, expansion of gases 2. (c) low temperature, high pressure 3. (c) gases and liquids behave like fluids 4. (d) evaporation 5. (c) oxygen, water, sugar 6. (a) 298 K, 311 K and 339 K 7. (b) conversion of vapours into solid without passing through

the liquid state is called sublimation 8. (c) 308 K, 329 K, 391 K 9. (d) increase in temperature of water 10. (c) (ii) and (iii)

Short Answer Type Questions11. A sample of water under study was found to boil at 102°C at

normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment.

Ans. It is impure water because pure water boils at 100ºC at normal temperature and pressure. Its freezing point will be below 0°C due to the presence of non-volatile impurities in it.

12. A student heats a beaker containing ice and water. He measures the temperature of the contents of the beaker as a function of time. Which of the following would correctly represent the result? Justify your choice.

0°C

100°C

Tem

pera

ture

Time (min.)(a)

0°C

100°C

Tem

pera

ture

Time (min.)(d)

0°C

100°C

Tem

pera

ture

Time (min.)(b)

0°C

100°C

Tem

pera

ture

Time (min.)( )c

Ans. Since ice and water are in equilibrium initially, the temperature would be zero. When we heat the mixture, energy supplied is used in melting the ice and the temperature does not change till whole ice melts because of latent heat of fusion. On further heating, the temperature of the water would rise. Therefore the correct answer is (d).



13. Fill in the blanks: (a) The phenomenon of change of a liquid into the gaseous state

at any temperature below its boiling point is called ________ . (b) ________ is the change of gaseous state directly to solid state

without going through the ________ state. (c) Evaporation of a liquid at room temperature leads to a

________ effect. (d) At room temperature the forces of attraction between the

particles of solid substances are ________ than those which exist in the gaseous state.

(e) The arrangement of particles is less ordered in the ________ state. However, there is no order in the ________ state.

Ans. (a) evaporation (b) sublimation, liquid (c) cooling (d) stronger (e) liquid, gaseous14. Match the physical quantities given in column A to their SI units

given in column B: (A) (B) (a) Mass (i) cubic metre (b) Density (ii) kilogram (c) Volume (iii) pascal (d) Temperature (iv) kelvin (e) Pressure (v) kilogram per cubic metreAns. (a) (ii) (b) (v) (c) (i) (d) (iv) (e) (iii)15. The non-SI and SI units of some physical quantities are given in

column A and column B respectively. Match the units belonging to the same physical quantity:

(A) (B) (a) bar (i) kilogram (b) milligram (ii) pascal (c) gram per centimetre cube (iii) metre (d) centimetre (iv) kelvin (e) degree celsius (v) kilogram per cubic metreAns. (a) (ii) (b) (i) (c) (v) (d) (iii) (e) (iv)16. ‘Osmosis is a special kind of diffusion’. Comment. Ans. Yes, this is true. In both the phenomena, there is a movement of

particles from a region of higher concentration to a region of lower concentration. However, in the case of osmosis, the movement of solvent is through a semipermeable membrane which allows only solvent molecules to pass through it.


MBD NCERT Solutions Science ForClass-IX

Publisher : MBD GroupPublishers

ISBN : 9789387763364Author : MBD GroupPublishers

Type the URL : http://www.kopykitab.com/product/16354

Get this eBook

40%OFF

https://www.kopykitab.com/MBD-NCERT-Solutions-Science-For-Class-IX-by-MBD-Group-Publishers

Documents

Done 16-1-18 - Kopykitab