What was the fissionable material used in the bomb dropped at Nagasaki (Japan) in the year $1945$?

$A$ nuclear reactor provides a power of $300 \, MW$. If the fission of one uranium nucleus ${U^{235}}$ releases $170 \, MeV$ of energy,how many nuclei undergo fission in $1 \, h$?

When a proton collides with a $_3Li^7$ nucleus and results in a $_4Be^8$ nucleus,the emitted particle is:

Which one of the following is not correct?

The energy released by the fission of a single uranium nucleus is $200 \,MeV$. The number of fissions of uranium nucleus per second required to produce $16 \,MW$ of power is (Assume efficiency of the reactor is $50\%$).

The electrostatic energy of a nucleus of charge $Ze$ is equal to $\frac{k Z^2 e^2}{R}$,where $k$ is a constant and $R$ is the nuclear radius. The nucleus divides into two daughter nuclei of charges $\frac{Ze}{2}$ and equal radii. The change in electrostatic energy in the process when they are far apart is