Question

The total number of isotopes of hydrogen and the number of radioactive isotopes among them, respectively, are:

• A. $2$ and $0$
• B. $3$ and $2$
• C. $3$ and $1$
• D. $2$ and $1$

Answer 1

The correct option is C $3$ and $1$

Total number of isotopes of hydrogen is $3$

$⟹{}_2^{1}H,{}_1^{2}H$ or ${}_1^{3}D,{}_1^{3}H$ or ${}_1^{3}T$

and only ${}_1^{3}H$ or ${}_1^{3}T$ is a radioactive element.

Hence, the correct option is C.