How much energy is produced from the combustion of $1\, kg$ of coal?

Mention the use of controlled nuclear fission. Mention the use of uncontrolled nuclear fission.

$A$ nucleus with mass number $240$ breaks into two fragments each of mass number $120$. The binding energy per nucleon of the unfragmented nucleus is $7.6 \, MeV$,while that of the fragments is $8.5 \, MeV$. The total gain in the binding energy in the process is (in $MeV$):

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):

The average energy of a neutron produced in the fission of ${ }_{92}^{235} U$ is

In the proton-proton cycle, four hydrogen nuclei combine to release energy of ....... $MeV$.