The atomic number of a nucleus after a $\beta$-emission from a nucleus with an atomic number of $40$ will be:

During the emission of a $\beta$-particle,what happens to the nucleus?

Identify $[A]$ and $[B]$ in the following reaction sequence:
${ }_{89}^{227} Ac$ $\xrightarrow{-\beta} [A]$ $\xrightarrow{-\alpha} [B]$ $\xrightarrow{-\alpha} { }_{86}^{219} Rn$

Which of the following is used in dating archaeological findings,or in a method of absolute dating of fossils,a radioactive element is used. It is:

$_{72}^{180}X$ $\xrightarrow{2\alpha}$ $\xrightarrow{\beta}$ $\xrightarrow{\gamma} _{Z}^{A}X'$. The values of $Z$ and $A$ are:

$^{14}C$ is radioactive. The activity and the disintegration product are