In the reaction $_{93}Np^{239} \xrightarrow{} _{94}Pu^{239} + (?)$,the missing particle is

After the emission of one $\alpha$-particle followed by one $\beta$-particle from the atom of $_{92}X^{238}$,the number of neutrons in the atom will be

If by mistake some radioactive substance gets inside the human body,then from the point of view of radiation damage,the most harmful will be the one which emits

Tritium undergoes radioactive decay giving

What is the symbol for the nucleus remaining after $_{20}Ca^{42}$ undergoes $\beta$-emission?

After the emission of a $\beta$-particle followed by an $\alpha$-particle from ${ }_{83}^{214} Bi$,the number of neutrons in the resulting atom is: