NEET Physics - New - Nuclear Physics and Radioactivity

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Question - 1

The ratio of the nuclear radii of  \(\mathrm{Cs}^{135} \text { to } \mathrm{Ca}^{40}\) is

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

Question - 2

The ratio of radii of nuclei 13AI27 and 52XA is 3:5. The number of neutrons in the nuclei of X will be

  • A 52
  • B 73
  • C 125
  • D 13

Question - 3

Find the density of \(\begin{array}{l} 12 \\ 6 \end{array}\)C nucleus.
 

  • A 2.7 x 10-17 kg/m3
  • B 2.4 x 1017 kg/m3
  • C 2.7 x 1015 kg/m3
  • D 2.4 x 10-15 kg/m3

Question - 4

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

  • A \({ }_Z^A X+\gamma \rightarrow{ }_{Z-1}^A X+a+b\)
  • B \({ }_Z^A X+{ }_0^1 n \rightarrow{ }_{Z-2}^{A-3} X+c\)
  • C \({ }_Z^A X+{ }_{-1}^0 e \rightarrow{ }_{Z-1}^A X+g\)
  • D \({ }_Z^A X^* \rightarrow{ }_Z^A X+f\)

Question - 5

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

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

Question - 6

A radioactive nucleus undergoes \(\alpha\)-emission to form a stable element. What will be the recoil velocity of the daughter nucleus, if v is the velocity of \(\alpha\)-emission and
A is the atomic mass of radioactive nucleus?

  • A \(\frac{4 v}{A-4}\)
  • B \(\frac{2 v}{A-4}\)
  • C \(\frac{4 v}{A+4}\)
  • D \(\frac{2 v}{A+4}\)

Question - 7

If one starts with one curie of radioactive substance (T1/2 = 12 h), 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 - 8

The half-life of radioactive radon is 3.8 day. The time at the end of which 1/20th of the radon samnple will remain undecayed is (Given, log10e = 0.4343)

  • A 3.8 day
  • B 16.5 day
  • C 33 day
  • D 76 day

Question - 9

A radioactive isotope X with a half-life of 1.37 x 109 yr 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 1.96 x 108 yr
  • B 3.85 x 109 yr
  • C 4.1l x 109 yr
  • D 9.59 x 109 yr

Question - 10

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

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