If the mass defect of ${ }_{5}^{11}B$ is $0.081 \ u$, its average binding energy (in $MeV$) is

In the successive emission of $\alpha$- and $\beta$-particles,the number of $\alpha$- and $\beta$-particles that should be emitted for the conversion of ${}^{238}_{92}U$ to ${}^{206}_{82}Pb$ are:

$A$ nuclear reaction is accompanied by a loss of mass equivalent to $0.01864 \; amu$. The energy liberated is .......... $MeV$.

The isotopic mass of ${}_{3}^{7}Li$ is $7.016005 \ u$ and those of the $H$ atom and neutron are respectively $1.007825 \ u$ and $1.008665 \ u$. Then,the binding energy of the ${}_{3}^{7}Li$ nucleus is: (in $MeV$)

In the radioactive decay,${}_{Z}^{A}X \to {}_{6}^{12}C + {}_{+1}^{0}e$,find the values of $A$ and $Z$.

Ordinary water is not used as a moderator in nuclear reactors because