CBSE Physics (Chapter Wise With Hint / Solution) Class XII
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PHYSICS  CBSE CLASS XII
Atomic Nucleus
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1) what conclusions were drawn from the observation in which few alphaparticle
were seen rebounding from gold foil?
2) which observation led to the conclusion in the αparticle scattering exp. That atom
has vast empty space?
3) Compare the radii of two nuclei with mass number 1 and 27 respectively.
4) Two nuclei have mass numbers in the ratio 1:8.What is the ratio of their nuclear
radii?
5) which have greater ionizing power:αparticles or βparticles?
6) The half life of a radioactive substance in 30 days. What is the time taken for ¾
of its original mass to disintegrate?
7) Why neutrons are considered as ideal particle for nuclear reactions?
8) Does the ratio of neutrons and protons in the nucleus increase, decreases or
remain the same after the emission of ά – particles?
9) Why is the ionization power of ά – particle of greater than γ – rays?
10) A radio isotope of silver has a half life of 20 minutes. What fraction of the
original mass would remain after one hour?
11) What changes takes place in the nucleus when a γ – rays is emitted?
12) Can a single nucleus emit ά – particle, β – particle and a γ – rays together?
13) Two nuclei have mass no. in the ratio 1:2. What is the ratio their nuclear
densities?
14) Establish the relationship between half life of a radio active substance and
decay constant.
15) Explain how ά particle scattering experiment led to Rutherford to estimate the
size of the
nucleus.
16) The activity of a radio active material drops to 116th of its initial value in 30
days. Find its
half life.
17) In a particular fission reaction, a U 235 nucleus captures a slow neutron. The
fission products are 3 neutrons, a La 142 and fission products X y z .What is
the value of Y and Z.
18) You are given two nuclides Xb) Which one of the two is likely to be more stable? Give reason.
19) A certain radio active substance has a half life of 30 days. What is the
disintegration
constant? Find its average life.
20) Find the time required to decay 3/4th of a radioactive sample whose half life is
60 days.
21) Neon 23 decays in the following way
^{23}Ne_{10} ^{23}Ne_{10} + ^{0}e_{1} +γ
Find the minimum and maximum kinetic energy that the βparticle can have.
The atomic masses of ^{23}Ne_{10} and ^{23}Ne_{10} are 22.99454 and 22.98984
respectively.
22) The disintegration rate of a certain radioactive sample at any instant is 4750
disintegrations per minute. Five minutes later the rate becomes 2700 per
minute. Calculate
a) Decay constant
b) Halflife of the sample
23) Explain with an example, whether neutronproton ratio increases or
decreases during beta decay.
24) The half life period of radioactive element A is the same as the mean half time
of another radioactive element B.Initially both of them have the same number of
atoms. The radioactive element B decays faster than A. Explain why?
25) Obtain the binding energy of a nitrogen nucleus from the following data
mh=1.007834; mn=1.00867; mN=14.03074
Give your answer in MeV.
26) Write nuclear equations for
a) The αdecay of ^{226}Ra_{88}
b) The β decay of ^{32}P_{15}
c) The β+ decay of^{32}P_{15}
27) A neutron is absorbed by a ^{6}Li_{3} nucleus with the subsequent emission of an
alpha particle.
i) Write the corresponding nuclear reactions.
ii) Calculate the energy released in MeV, in this reaction.
Given mass ^{6}Li_{3}=6.0151264; mass (neutron) =1.00966544
Mass (alpha particle)=4.00260444 and mass(triton)=3.01000004
CBSE Physics (Chapter Wise With Hint / Solution) Class XII (By Mr. Sreekumaran Nair)
Physics  Mr. Sreekumaran Nair
