The carbon dating is based on

$\beta$-emission is always accompanied by

Which metal is used in radiation shielding?

$A$ radioactive nuclide $X$ decays at the rate of $1.00 \times 10^5 \ disintegration \ s^{-1} \ g^{-1}$. Radium decays at the rate of $3.70 \times 10^{10} \ disintegration \ s^{-1} \ g^{-1}$. The activity of $X$ in millicuries $g^{-1}$ $(mCi \ g^{-1})$ is

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

$C_{6}H_{5}F^{18}$ is an $F^{18}$ radio-isotope labelled organic compound. $F^{18}$ decays by positron emission. The product resulting from the decay is: