The activity of a radioisotope changes with:

The binding energy of $_8O^{16}$ is $127 \ MeV$. Its binding energy per nucleon is ...... $MeV$.

The element $_{90}Th^{232}$ belongs to the thorium series. Which of the following will act as the end product of this series?

Calculate the mass defect in the following nuclear reaction:
$_1H^2 + _1H^3 \to _2He^4 + _0n^1$
(Given: mass of $_1H^2 = 2.014 \ amu$,$_1H^3 = 3.016 \ amu$,$_2He^4 = 4.004 \ amu$,$_0n^1 = 1.008 \ amu$) (in $amu$)

The atomic mass of lead is $208$ and atomic number is $82$. The atomic mass of bismuth is $209$ and atomic number is $83$. The ratio of $n/p$ in the atom is

Who observed that when the nucleus of a uranium atom was bombarded with fast-moving neutrons,it became so unstable that it immediately broke into two nuclei of nearly equal mass,besides other fragments?