Choose the correct option to complete the net effect of the fusion reaction that occurs in the Sun: $4_1^1H + 2e^- \rightarrow$ . . . . . . $+ 2\nu + 6\gamma +$ . . . . . .

$A$ nuclear reactor with $40\%$ efficiency produces $10^{14}$ fissions per second. Each fission releases $250 \text{ MeV}$ of energy. The power output of the reactor is ......... $W$.

The best neutron moderator is:

The explosive in a Hydrogen bomb is a mixture of ${ }_1 H^2, { }_1 H^3$ and ${ }_3 Li^6$ in some condensed form. The chain reaction is given by:
${ }_3 Li^6 + { }_0 n^1 \rightarrow { }_2 He^4 + { }_1 H^3$
${ }_1 H^2 + { }_1 H^3 \rightarrow { }_2 He^4 + { }_0 n^1$
During the explosion,the energy released is approximately:
[Given: $M(Li^6) = 6.01690 \ amu, M({ }_1 H^2) = 2.01471 \ amu, M({ }_2 He^4) = 4.00388 \ amu$,and $1 \ amu = 931.5 \ MeV$] (in $MeV$)

$A$ $1000 \; MW$ fission reactor consumes half of its fuel in $5.00 \; y$. How much $_{92}^{235} U$ (in $kg$) did it contain initially? Assume that the reactor operates $80 \%$ of the time, that all the energy generated arises from the fission of $_{92}^{235} U$, and that this nuclide is consumed only by the fission process.

The function of a moderator in a nuclear reactor is: