Which among the following minerals contains a radioactive element?

If radium and chlorine combine to form radium chloride,the compound is:

Ordinary water is not used as a moderator in nuclear reactors because

The isotopic mass of ${}_{3}^{7}Li$ is $7.016005 \ u$ and those of the $H$ atom and neutron are respectively $1.007825 \ u$ and $1.008665 \ u$. Then,the binding energy of the ${}_{3}^{7}Li$ nucleus is: (in $MeV$)

If the binding energy per nucleon of $_1H^2$ is $x$ and that of $_2He^4$ is $7x$,then the ratio of the energy liberated in the reaction $_1H^2 + _1H^2 \to _2He^4$ to the binding energy per nucleon of $_1H^2$ is:

Which of the following statements about radioactivity of an element is incorrect?