$\gamma$-rays radiation can be used to create electron-positron pair. In this process of pair production, $\gamma$-rays energy cannot be less than .......$MeV$

In an $\alpha -$ decay, the kinetic energy of $\alpha -$ particle is $48\, MeV$ and $Q$ value of the reaction is $50\, MeV$. The mass number of the mother nucleus is [assume that daughter nucleus is inground state]

Statement $-1$ : A nucleus having energy $E _{1}$ decays $\beta^{-}$ emission to daughter nucleus having energy $E _{2}$ but the $\beta^{-}$rays are emitted with a continuous energy spectrum having end point energy $E _{1}- E _{2}$

Statement $-2$ : To conserve energy and momentum in $\beta$ decay at least three particles must take part in the transformation.

The correct order of ionizing capacity of $\alpha ,\;\beta $ and $\gamma - $ rays is

A neutron strikes a ${ }_{92} U ^{235}$ nucleus and as a result ${ }_{38} Kr ^{93}$ and ${ }_{56} Ba ^{140}$ are produced with

Which ray contain positively charged particle