A nucleus of mass number \(189\) splits into two nuclei having mass numbers \(125\) and \(64.\) The ratio of the radius of two daughter nuclei respectively is:

1.	\(25:16\)	2.	\(1:1\)
3.	\(4:5\)	4.	\(5:4\)

A radioactive nucleus \(_{\mathrm{Z}}^{\mathrm{A}}\mathrm{X}\) undergoes spontaneous decay in the sequence \(_{\mathrm{Z}}^{\mathrm{A}}\mathrm{X}\rightarrow \mathrm{B}_{\mathrm{Z-1}}\rightarrow \mathrm{C}_{\mathrm{Z-3}}\rightarrow \mathrm{D}_{\mathrm{Z-2}}\) where \(\mathrm{Z}\) is the atomic number of element \(\mathrm{X}\). The possible decay particles in the sequence are: 

A nucleus with mass number \(240\) breaks into fragments each of mass number \(120\). The binding energy per nucleon of unfragmented nuclei is \(7.6\) MeV while that of fragments is \(8.5~\text{MeV}\). The total gain in the binding energy in the process is:

If a ${}_a{}^{b}X$ species emits firstly a positron, then two $\alpha$ and two β and at last one $\alpha$ is also emitted and finally convert into stable ${}_d{}^{c}Y$ species, so the correct relation will be: 
1.  c = b – 12,  d = a – 5
2.  a = c – 8,   d = b – 1
3.  a = c – 6,   d = b – 0
4.  a = c – 4,   a = b – 2

A nuclear reaction is given by

${}_{\mathrm{Z}}{\mathrm{X}}^{\mathrm{A}}{\to }_{\mathrm{Z}+1}{\mathrm{Y}}^{\mathrm{A}}{+}_{-1}{\mathrm{e}}^0+\overline{\mathrm{v}}$

represents:

1. β-decay

2. γ-decay

3. fusion

4. fission

The mass number of a nucleus is:

The mass of a proton is 1.0073 u and that of a neutron is 1.0087 u (u = atomic mass unit). The binding energy of ${}_2{}^4\mathrm{He}$ is: (Given: helium nucleus mass ≈ 4.0015 u)

Which of the following rays are not electromagnetic waves?

1. X-rays

2. γ-rays

3. β-rays

4. Heat rays

The volume occupied by an atom is greater than the volume of the nucleus by a factor of about:
1. \(10\)
2. \(10^5\)
3. \(10^{10}\)
4. \(10^{15}\)