The age of the most ancient geological formations is estimated by:

$A$ closed vessel with rigid walls contains $1 \ mol$ of ${ }_{92}^{238} U$ and $1 \ mol$ of air at $298 \ K$. Considering the complete decay of ${ }_{92}^{238} U$ to ${ }_{82}^{206} Pb$, the ratio of the final pressure to the initial pressure of the system at $298 \ K$ is:

Radioactive iodine is used to diagnose the disease of

In the sequence of the following nuclear reactions $_{92}X^{238}$ $\xrightarrow{-\alpha} Y$ $\xrightarrow{-\beta} Z$ $\xrightarrow{-\beta} L$ $\xrightarrow{-n\alpha} _{84}M^{218}$. The value of $n$ will be:

The radioactive isotope $_{27}^{60}Co$,which is used in the treatment of cancer,can be produced by an $(n, p)$ reaction. For this reaction,the target nucleus is:

In the nuclear transmutation $_4^9 Be + X \longrightarrow _4^8 Be + Y$,the pair $(X, Y)$ is (are):