When neutrons are bombarded on the nucleus of $_{92}^{235}U$,the number of emitted neutrons is typically

The binding energy per nucleon for ${}_1^2H$ and ${}_2^4He$ are $1.1 \; MeV$ and $7.1 \; MeV$ respectively. The energy released in $MeV$ when two ${}_1^2H$ nuclei fuse to form one ${}_2^4He$ nucleus is:

If $1 \, g$ of hydrogen is converted into $0.993 \, g$ of helium in a thermonuclear reaction,the energy released in the reaction is ......... $J$.

The energy released if hydrogen atoms are combined to form $^{4}_{2}He$ is . . . . . . MeV. (Take binding energies per nucleon of $^{2}H$ and $^{4}_{2}He$ as $1.1$ MeV and $7.2$ MeV,respectively)

Explain an example in which heat transfer is necessary.

The rest mass of an electron as well as that of a positron is $0.51 \, MeV$. When an electron and a positron annihilate, they produce gamma-rays of wavelength(s):