Physics - Nuclear Physics and Radioactivity

Question - 1

The ratio of the nuclear radii of Cs135 to Ca40 is

  • A 1.35
  • B 3.375
  • C 1.84
  • D 1.5

Question - 2

Find the density of \(^{12}_6C\) nucleus.

  • A 2.7X10-17 kg/m3
  • B 2.4X1017 kg/m3
  • C 2.7X1015 kg/m3
  • D 2.4X10-15 kg/m3

Question - 3

Assuming that all laws of thermodynamics can be applied to a nucleus, the \(\alpha\)-decay of a nucleus may be regarded as an

  • A isothermal process
  • B isobaric process
  • C adiabatic process
  • D isochoric process

Question - 4

Which one of the following processes represents a \(\gamma \ decay\)?

  • A \(^A_ZX+\gamma\rightarrow ^A_{Z-1}X+a+b\)
  • B \(^A_ZX+^1_0n\rightarrow ^{A-3}_{Z-2}X+c\)
  • C \(^A_ZX+^o_{-1}e\rightarrow ^A_{Z-1}X+g\)
  • D \(^A_ZX^*\rightarrow ^A_{Z}X+f\)

Question - 5

The half-life of 131I is 8 day. Given a sample of 131I at time t=0, we can assert that

  • A no nucleus will decay before t=4 days
  • B no nucleus will decay beore t=8 days
  • C all nuclei will decay before t=16 days
  • D given nucleus may decay at any time after t=0

Question - 6

If one starts with one curie of radioactive substance (T1/2=12h), then the activity left after a period of 1 week will be about

  • A 1 curie
  • B 120 micro curie
  • C 60 micro curie
  • D 8 mili curie

Question - 7

A radioactive isotope X with a half-life of 1.37X109yr decays to Y which is stable. A sample of rock from the moon was found to contain both the elements X and Y which were in the ratio of 1:7. The age of the rock is

  • A 1.96X108 yr
  • B 3.85X109yr
  • C 4.11X109yr
  • D 9.59X109yr

Question - 8

A and B are two radioactive substances whose half-lives are 1 and 2 yr respectively. Initially, 10g of A and 1g of B is taken. The time (approximate) after which they will have same quantity remaining is

  • A 6.62 yr
  • B 5 yr
  • C 3.2yr
  • D 7 yr

Question - 9

The ratio of half-life and mean life of a radioactive sample is

  • A ln 2
  • B 1
  • C \(1\over ln \ 2\)
  • D \(1\over 2\ ln \ 2\)

Question - 10

From a newly formed radioactive substance (Half-life 2 h), the intensity of radiation is 64 times the permissible safe level. The minimum time after which work can be done safely from this source is

  • A 6h
  • B 12h
  • C 24h
  • D 128h