In nuclear fission, the percentage of mass converted into energy is about

1.  1%

2.  0.1%

3.  0.01%

4.  10%

The mass number of helium is 4 and that for suphur is 32. The radius of sulphur nuclei is larger than that of helium by

1.  $\sqrt{8}$

2.  4

3.  2

4.  8

In the nuclear decay given below

${}_{\mathrm{z}}{}^{\mathrm{A}}\mathrm{X} \stackrel{}{\to } {}_{\mathrm{Z} + 1}{}^{\mathrm{A}}\mathrm{Y} \stackrel{}{\to } {}_{\mathrm{Z} - 1}{}^{\mathrm{A} - 4}\mathrm{B}_{*} \stackrel{}{\to } {}_{\mathrm{Z} - 1}{}^{\mathrm{A} - 4}\mathrm{B},$

$\mathrm{The} \mathrm{particles} \mathrm{emitted} \mathrm{in} \mathrm{the} \mathrm{sequence} \mathrm{are}$
$$

1.  $\mathrm{\beta }, \mathrm{\alpha }, \mathrm{\gamma }$

2.  $\mathrm{\gamma }, \mathrm{\beta }, \mathrm{\alpha }$

3.  $\mathrm{\beta }, \mathrm{\gamma }, \mathrm{\alpha }$

4.  $\mathrm{\alpha }, \mathrm{\beta }, \mathrm{\gamma }$

$In the nucleus of {}_{11}{}^{23}Na, \mathrm{the} \mathrm{number} \mathrm{of} \mathrm{protons}, \mathrm{neutrons} \mathrm{and} \mathrm{electrons} \mathrm{are}$:

1.  11, 12, 0

2.  23, 12, 11

3.  12, 11, 0

4.  23, 11, 12

A thorium nucleus is formed when a uranium nucleus emits an $\mathrm{\alpha } - \mathrm{particle}$. The atomic number of thorium is

1.  92

2.  90

3.  82

4.  94

The activity of the radioactive element decreases to one-third of the original activity ${\mathrm{A}}_0$ in a period of 7 years. After a further lapse of 7 years, its activity will be:

1.  ${\mathrm{A}}_0$ $$ $$

2.  $\frac{2}{3}{\mathrm{A}}_0$ $$ $$

3.  $\frac{{\mathrm{A}}_0}{6}$ $$ $$

4.  $\frac{{\mathrm{A}}_0}{9}$

The radius of Germanium (Ge) nuclide is measured to be twice the radius of ${}_4{}^9\mathrm{Be}$. The number of nucleons in Ge is:

1. 73

2. 74

3. 75

4. 72

A radioactive nucleus X decays to a stable nucleus 'y'. The graph of the rate of formation of 'y' against time 't' will be:

1.		2.
3.		4.

A stationary radioactivity nucleus of mass 210 units disintegrates into an alpha particle of mass 4 units and residual nucleus of mass 206 units. If the kinetic energy of the alpha particles is E, the kinetic energy of the residual nucleus is 

1.  $\left(\frac{2}{105}\right) \mathrm{E}$

2.  $\left(\frac{2}{103}\right) \mathrm{E}$

3.  $\left(\frac{103}{105}\right) \mathrm{E}$

4.  $\left(\frac{103}{2}\right) \mathrm{E}$