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8/11/2019 DPPS___4__Nulcear_Physics___Radioactive__10-6-14
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CAREER POINT
PRACTICE PROBLEM SHEET
PHYSICS
Topic Nuclear Physics & Radioactivity-1
Q.1 A star of mass M0, radius R0contracts to radius R. Energy radiated by the star assuming uniform density in
each case while temperature remains unchanged is -
(1M0c! (! M0c
!
!
0
"1R
R(#M0c
!
0
"1R
R($M0c
!
#
0
"1R
R
Q.2 %he total energy E of a sub-atomic particle of rest mass m0 mo&ing at non-relati&istic speed
& is -
(1E' m0c! (!E'
!
1m0&
! (#E' m0c!
!
1m0&
! ($E' m0c!"
!
1m0&
!
Q.3 )f udenotes 1 atomic mass unit. *ne atom of an element has mass e+actly eual to Au, where A is mass
number of element -
(1A' 1 (!A' 1!
(#A' 1 ($ A can tae up any integral &alue from 1 to 110
Q.4 /ast neutrons can easily be slowed down by -
(1 the use of lead shielding (! passing them through hea&y water
(# elastic collisions with hea&y nuclei ($ applying a strong electric field
Q.5 hich of the following statements is correct -
(1 eta rays are same as cathode rays (! 2amma rays are high energy neutrons
(# Alpha particles are singly ioni3ed helium atoms ($ 4rotons and neutrons ha&e e+actly the same mass
Q.6 Mar the correct statement -
(1 E&ery element has only two stable isotopes
(! All isotopes of e&ery element are radioacti&e
(# *nly one isotope of each element is stable
($ 5uclei of different elements can ha&e the same number of neutrons
Q. %he chemical beha&iour of an atom depends upon -
(1 the number of nucleons in its nucleus (! the number of protons in its nucleus
(# the number of neutrons in its nucleus ($ the number of electrons in its atom
Q.! 6uring a nuclear fusion reaction 7CAREER POINT, CP Tower, IPIA, Road No.1, Kota (Raj.), Ph: 0744-3040000 1
CP Live Enthuse Class XII -2015
PRE
"PPS #$ - 0% 6iscussion on 71"-6-2"14
8/11/2019 DPPS___4__Nulcear_Physics___Radioactive__10-6-14
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(1 a hea&y nucleus breas into two fragments by itself
(! a light nucleus bombarded by thermal neutrons breas up
(# a hea&y nucleus bombarded by thermal neutrons breas up
($ two light nuclei combine to gi&e a moderate nucleus and possibly other products
Q.# oron rods in a nuclear reactor are used to -
(1 absorb e+cess neutrons (! absorb alpha-particles
(# slow down the reaction ($ speed up the reaction
Q.1" hich of the following statement (s is (are correct 8
(1 %he rest mass of a stable nucleus is less than the sum of the rest masses of its separated nucleons.
(! %he rest mass of a stable nucleus is greater than the sum of the rest masses of its separated nucleons.
(# )n nuclear fusion, energy is released by fusing two nuclei of medium mass (appro+imately. 100 amu
($ 5one of these
Q.11 9et mpbe the mass of a proton, m
nthe mass of neutron, M
1the mass of a
105e!0nucleus and M
!the mass of a
!0:a$0
nucleus. %hen -
(1 M!' !M
1(! M
!; !M
1(# M
!< !M
1($ M
1< 10 (m
n m
p
Q.12 *rder of magnitude of density of =ranium nucleus is,>mp' 1.? @ 10"!?g
(1 10!0gBm# (! 101?gBm# (# 101$gBm# ($ 1011gBm#
Q.13 inding energy per necleon &ersus mass number cur&e for nuclei is shown in the figure. , C, D and are
four neclei indicated on the cur&e. %he process that would release energy is 7
(1 D! (! C (# !D ($ C ' D
Q.14 )n a star all Felium nuclei are con&erted into o+ygen. )f atomic mass of MFe
' $.00!= and atomic mass of
o+ygen M0' 1G.HHH$=, then the reaction energy per atom of o+ygen -
(1 10.! MeI (! 0 MeI (# G.!$ MeI ($ !0.$ MeI
Q.15 %he nucleus of element C (A ' !!0 undergoes -decay. )f J-&alue of the reaction is G.G MeI, then
appro+imate inetic energy of -particle is -
(1 G. MeI (! G.$ MeI (# $.H MeI ($ .G MeI
CAREER POINT, CP Tower, IPIA, Road No.1, Kota (Raj.), Ph: 0744-3040000 !
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ANSWERS$
1.%4 6ensity of star of mass M0, radius R0 is '
#0
0
#
$R
M
*n contracting the new mass becomes
M'#
$R#'M0
#
0
R
R
9oss in mass due to contraction ' " M
Loss = M0 M
Energy radiated ' c!M
2.%3 E' mc!
E' m0c!
!B1
!
!
"1
c
V
Kincec
&