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

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

The explosion of the atomic bomb takes place due to

1. Nuclear fission           

2. Nuclear fusion

3. Scattering               

4. Thermionic emission

Fusion reaction is initiated with the help of 

(1) Low temperature         

(2) High temperature

(3) Neutrons                     

(4) Any particle

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

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

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 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