In the nuclear reaction  ${}_{85}{}^{297}\mathrm{X}\to \mathrm{Y}+4\mathrm{\alpha }$, Y is 

1. ${}_{76}\mathrm{Y}_{287}$            

2. ${}_{77}\mathrm{Y}_{285}$

3. ${}_{77}\mathrm{Y}_{281}$             

4. ${}_{77}\mathrm{Y}_{289}$

Which of these is a fusion reaction 

(1) ${}_1{}^3\mathrm{H}+{}_1{}^2\mathrm{H}\to {}_2{}^4\mathrm{He}+{}_0{}^1\mathrm{n}$

(2) ${}_{92}{}^{238}\mathrm{U}\to {}_{82}{}^{206}\mathrm{Pb}+8\left({}_2{}^4\mathrm{He}\right)+6\left({}_{-1}{}^0\mathrm{\beta }\right)$

(3) ${}_7{}^{12}\mathrm{C}\to {}_6{}^{12}\mathrm{C}+{\mathrm{\beta }}^{+}+\mathrm{\gamma }$

(4) None of these

Which one of the following nuclear reactions is a source of energy in the sun 

(1) ${}_4{}^9\mathrm{Be}+{}_2{}^4\mathrm{He}\to {}_6{}^{12}\mathrm{C}+{}_0{}^{-1}\mathrm{n}$

(2) ${}_2{}^3\mathrm{He}+{}_2{}^3\mathrm{He}\to {}_2{}^4\mathrm{He}+{}_1{}^1\mathrm{H}+{}_1{}^1\mathrm{H}$

(3) ${}_{56}{}^{144}\mathrm{Ba}+{}_{56}{}^{92}\mathrm{Kr}\to {}_{92}{}^{235}\mathrm{U}+{}_0{}^{-1}\mathrm{n}$

(4) ${}_{26}{}^{56}\mathrm{Fe}+{}_{48}{}^{112}\mathrm{Ca}\to {}_{74}{}^{167}\mathrm{W}+{}_0{}^{-1}\mathrm{n}$

Which of the following particle has similar mass to electron

(1) Proton             

(2) Neutron

(3) Positron           

(4) Neutrino

In a nuclear fission reaction 

(1) Two light nuclei combine to produce a heavier nucleus

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

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

(4) A heavy nucleus breaks up by itself

Thermal neutrons can cause fission in 

(1) ${\mathrm{U}}^{235}$          

(2) ${\mathrm{U}}^{238}$

(3) ${\mathrm{Pu}}^{238}$        

(4) ${\mathrm{Th}}^{232}$

The number of neutrons released when ${}_{92}\mathrm{U}_{235}$ undergoes fission by absorbing ${}_0{}^1\mathrm{n}$ and $\left({}_{56}{}^{144}\mathrm{Ba}+{}_{36}{}^{89}\mathrm{Kr}\right)$are formed, is 

(1) 0           

(2) 1

(3) 2         

(4) 3

Hydrogen bomb is based on which of the following phenomenon

(1) Nuclear fission             

(2) Nuclear fusion

(3) Radioactive decay       

(4) None of these

When neutrons are bombarded on nucleus of ${}_{92}\mathrm{U}_{235}$, the number of emitted neutrons will be 

(1) 1         

(2) 2

(3) 3         

(4) 4

The energy released in a typical nuclear fusion reaction is approximately 

(1) 25 MeV           

(2) 200 MeV

(3) 800 MeV         

(4) 1050 MeV