The mass defect for the nucleus of helium is 0.0303 a.m.u. What is the binding energy per nucleon for helium in MeV?

1.  28

2.  7

3.  4

4.  1

In the reaction ${}_1{}^2\mathrm{H}+{}_1{}^3\mathrm{H} \stackrel{ }{\to } {}_2{}^4\mathrm{H}+{}_0{}^1\mathrm{n}$, if the binding energies of ${}_1{}^2\mathrm{H}, {}_1{}^3\mathrm{H}$ and ${}_2{}^4\mathrm{H}$ are respectively a, b and c (in MeV), then the energy (in MeV) released in this reaction is

1.  $\mathrm{a}+\mathrm{b}+\mathrm{c}$

2.  $\mathrm{a}+\mathrm{b}-\mathrm{c}$

3.  $\mathrm{c}-\mathrm{a}-\mathrm{b}$

4.  $\mathrm{c}+\mathrm{a}-\mathrm{b}$

Assume that the nuclear binding energy per nuclear (B/A) versus mass number (A) is as shown in the figure. Use this plot to choose the correct choice(s) given below:

1. Fusion of two nuclei with mass number lying in the range of 51<A<100 will release energy

2. Fusion of a nucleus lying in the mass range of 200<A<260 will release energy when broken into two equal fragments

3. Both A and B

4. None of these

The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is:

1. 15

2. 30

3. 45

4. 60

A radioactive nucleus \(X\) decays to a stable nucleus \(Y.\) Then, the graph of the rate of formation of \(Y\) against time \(t\) will be:

1.		2.
3.		4.

A nucleus of uranium decays at rest into nuclei of thorium and helium. Then:

Fission of nuclei is possible because the binding energy per nucleon in them-

1.  Decreases with mass number at low mass numbers

2.  Increases with mass number at low mass numbers

3.  Decreases with mass number at high mass numbers

4.  Increases with mass number at high mass numbers