List of top Physics Questions on Nuclei asked in Haryana PMT

The binding energy of deuteron is $2.2 \,MeV$ and that of $ _{2}^{4}He$ is $28 \,MeV$. If two deuterons are fused to form one $ _{2}^{4} He$, then the energy released is

Two radioactive substances $A$ and $B$ have decay constants 5 $\lambda$, and $\lambda$ respectively. At $t\, =\, 0$, they have the same number of nuclei. The ratio of number of nuclei of $A$ to those of $B$ will be $(1/e^2)$ after a time