If an electron and a positron annihilate, then the energy released is:

1. $3.2\times {10}^{-13}$ $\mathrm{J}$       

2. $1.6\times {10}^{-13}$ $\mathrm{J}$

3. $4.8\times {10}^{-13}$ $\mathrm{J}$           

4. $6.4\times {10}^{-13}$ $\mathrm{J}$

An atomic nucleus ${}_{90}{}^{232}\mathrm{Th}$ emits several $\mathrm{\alpha }$ and $\mathrm{\beta }$ radiations and finally reduces to ${}_{82}{}^{208}\mathrm{Pb}$. It must have emitted:
1. 4$\mathrm{\alpha }$ and 2$\mathrm{\beta }$             
2. 6$\mathrm{\alpha }$ and 4$\mathrm{\beta }$
3. 8$\mathrm{\alpha }$ and 24$\mathrm{\beta }$           
4. 4$\mathrm{\alpha }$ and 16$\mathrm{\beta }$

In nuclear reaction ${}_2{}^4\mathrm{He}+{}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}\to {}_{\mathrm{Z}+2}{}^{\mathrm{A}+3}\mathrm{Y}+\mathrm{B}$, \(\mathrm {B}\) denotes:

1. Electron           

2. Positron

3. Proton               

4. Neutron

The Binding energy per nucleon of \(^{7}_{3}\mathrm{Li}\) and \(^{4}_{2}\mathrm{He}\) nucleon are \(5.60~\text{MeV}\) and \(7.06~\text{MeV}\), respectively. In the nuclear reaction \(^{7}_{3}\mathrm{Li} + ^{1}_{1}\mathrm{H} \rightarrow ^{4}_{2}\mathrm{He} + ^{4}_{2}\mathrm{He} +Q\), the value of energy \(Q\) released is:
1. \(19.6~\text{MeV}\)
 2. \(-2.4~\text{MeV}\)
 3. \(8.4~\text{MeV}\)
4. \(17.3~\text{MeV}\)

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an:
1. Isobar of a parent.
2. Isomer of a parent.
3. Isotone of a parent.
4. Isotope of a parent.

If in nuclear reactor using U²³⁵ as fuel, the power output is 4.8 MW, the number of fissions per second is:
(Energy released per fission of U²³⁵ = 200 MeV watts, 1 eV = 1.6 X 10^–19 J)

1. 1.5×10¹⁷           

2. 3×10¹⁹           

3. 1.5×10²⁵           

4. 3×10²⁵

In the reaction

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

1.  c + a - b

2.  c - a - b

3.  a + b + c

4.  a + b - c

A nuclear reaction along with the masses of the particle taking part in it is as follows;

$A + B \to C + D + Q MeV$
$1.002 1.004 1.001 1.003$
$amu amu amu amu$

The energy Q liberated in the reaction is:

1. 1.234 MeV

2. 0.931 MeV

3. 0.465 MeV

4. 1.862 MeV

The binding energy per nucleon of deuterium and helium atom is 1.1 MeV and 7.0 MeV. If two deuterium nuclei fuse to form a helium atom, the energy released is:

1. 19.2 MeV

2. 23.6 MeV

3. 26.9 MeV 

4. 13.9 MeV

Which of the following is used as a moderator in nuclear reactors? 

1. Plutonium 

2. Cadmium 

3. Heavy water

4. Uranium