When four hydrogen nuclei combine to form a helium nucleus, then:

$A$ nuclear reactor provides power of $300 \, MW$. If $170 \, MeV$ of energy is released per fission of a $U^{235}$ nucleus, then the number of uranium atoms undergoing fission per hour is:

The operation of a nuclear reactor is said to be critical when the value of the neutron multiplication factor $K$ is:

Control rods used in nuclear reactors are made of:

In a reactor, $2 \, kg$ of ${ }_{92} U ^{235}$ fuel is fully used up in $30$ days. The energy released per fission is $200 \, MeV$. Given that the Avogadro number, $N_A = 6.023 \times 10^{26} \, \text{per kilo mole}$ and $1 \, eV = 1.6 \times 10^{-19} \, J$. The power output of the reactor is close to $..... \, MW$.

An atomic bomb consists of two pieces of $_{92}U^{235}$ and a source of: