On the bombardment of neutron with Boron. $\mathrm{\alpha }$-particle is emitted and product nuclei formed is

(1) ${}_6\mathrm{C}_{{}_{12}}$         

(2) ${}_3\mathrm{Li}_6$

(3) ${}_3\mathrm{Li}_7$           

(4) ${}_4\mathrm{Be}_9$

The average kinetic energy of the thermal neutrons is of the order of 

(1) 0.03 eV         

(2) 3 eV 

(3) 3 KeV           

(4) 3 MeV

Which of the following isotopes is normally fissionable ?

(1) ${}_{92}\mathrm{U}_{238}$             

(2) ${}_{93}\mathrm{Np}_{239}$

(3) ${}_{92}\mathrm{U}_{235}$             

(4) ${}_2\mathrm{He}_4$

The process by which a heavy nucleus splits into light nuclei is known as 

(1) Fission           

(2) $\mathrm{\alpha }$-decay

(3) Fusion             

(4) Chain reaction

The explosion of the atomic bomb takes place due to

1. Nuclear fission           

2. Nuclear fusion

3. Scattering               

4. Thermionic emission

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

Energy generation in stars is mainly due to

(1) Chemical reactions               

(2) Fission of heavy nuclei

(3) Fusion of light nuclei             

(4) Fusion of heavy nuclei

Fusion reaction is initiated with the help of 

(1) Low temperature         

(2) High temperature

(3) Neutrons                     

(4) Any particle

When a ${}_4{}^9\mathrm{Be}$ atom is bombarded with $\mathrm{\alpha }$ particles, one of the product of nuclear transmutation is ${}_6{}^{12}\mathrm{C}$. The other is 

(1) ${}_{-1}{}^0\mathrm{e}$           

(2) ${}_1{}^1\mathrm{H}$

(3) ${}_1{}^2\mathrm{D}$            

(4) ${}_0{}^1\mathrm{n}$

During the nuclear fusion reaction 

(1) A heavy nucleus breaks into two fragments by itself

(2) A light nucleus bombarded by thermal neutrons breaks up

(3) A heavy nucleus bombarded by thermal neutrons breaks up

(4) Two light nuclei combine to give a heavier nucleus and  possibly other products