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

If m, ${\mathrm{m}}_{\mathrm{n}}$ and ${\mathrm{m}}_{\mathrm{p}}$ are the masses of ${}_{\mathrm{Z}}\mathrm{X}_{\mathrm{A}}$ nucleus, neutron and proton respectively 

(1) $\mathrm{m}<\left(\mathrm{A}-\mathrm{Z}\right){\mathrm{m}}_{\mathrm{n}}+{\mathrm{Zm}}_{\mathrm{p}}$       

(2) $\mathrm{m}=\left(\mathrm{A}-\mathrm{Z}\right){\mathrm{m}}_{\mathrm{n}}+{\mathrm{Zm}}_{\mathrm{p}}$

(3) $\mathrm{m}=\left(\mathrm{A}-\mathrm{Z}\right){\mathrm{m}}_p+{\mathrm{Zm}}_{\mathrm{n}}$        

(4) $\mathrm{m}>\left(\mathrm{A}-\mathrm{Z}\right){\mathrm{m}}_{\mathrm{n}}+{\mathrm{Zm}}_{\mathrm{p}}$

${\mathrm{M}}_{\mathrm{n}}$ and ${\mathrm{M}}_{\mathrm{P}}$ represent mass of neutron and proton respectively. If an element having atomic mass M has N-neutron and Z-proton, then the correct relation will be

(1) $\mathrm{M}<\left[{\mathrm{NM}}_{\mathrm{n}}+{\mathrm{ZM}}_{\mathrm{p}}\right]$         

(2) $\mathrm{M}>\left[{\mathrm{NM}}_{\mathrm{n}}+{\mathrm{ZM}}_{\mathrm{p}}\right]$

(3) $\mathrm{M}=\left[{\mathrm{NM}}_{\mathrm{n}}+{\mathrm{ZM}}_{\mathrm{p}}\right]$         

(4) $\mathrm{M}=\mathrm{N}\left[{\mathrm{M}}_{\mathrm{n}}+{\mathrm{M}}_{\mathrm{p}}\right]$

The explosion of the atomic bomb takes place due to

1. Nuclear fission           

2. Nuclear fusion

3. Scattering               

4. Thermionic emission

If a ${\mathrm{H}}_2$ nucleus is completely converted into energy, the energy produced will be around

(1) 1 MeV               

(2) 938 MeV

(3) 9.38 MeV           

(4) 238 MeV

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

As compared ${}_{12}\mathrm{C}$ atom, ${}_{14}\mathrm{C}$ atom has

(1) Two extra protons and two extra electrons

(2) Two extra protons but no extra electrons

(3) Two extra neutrons and no extra electrons

(4) Two extra neutrons and two extra electrons

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