Identify the type of nuclear process given below:
$4\,_{1}H^{1} \to \,_{2}He^{4} + 2\,_{1}e^{0} + 2\nu + 26\,MeV$

What is a moderator? Name the material used as a moderator in a nuclear reactor.

If three helium nuclei combine to form a carbon nucleus,then the energy released in this reaction is $\times 10^{-2} \text{ MeV}$. (Given $1 \text{ u} = 931 \text{ MeV}/c^2$,atomic mass of helium $= 4.002603 \text{ u}$,atomic mass of carbon $= 12.000000 \text{ u}$)

In the Sun,the important source of energy is

The function of a moderator in a nuclear reactor is:

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):