Radioactive substances emit $\gamma$-rays,which are

The element with atomic number $84$ and mass number $218$ changes to another element with atomic number $84$ and mass number $214$. The number of $\alpha$ and $\beta$-particles emitted are respectively:

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

When a radioactive element emits an electron,the daughter element formed will have:

Which of the following radioisotopes is used as anticancerous?

The penetrating power of an $\alpha$-particle is: