A nucleus of an element ${}_{84}{X^{202}}$ emits an $\alpha $-particle first, $\beta $ -particle next and then a gamma photon. The final nucleus formed has an atomic number

A nucleus $_Z{X^A}$ emits $3 \alpha$ - particles and $5 \beta$ particle. The ratio of total neutrons and protons in the final nucleus is

A certain radioactive material $_ZX^A$ starts emitting $\alpha $ and $\beta $ particles successively such that the end product is $_{Z-3}Y^{A-8}$. The number of $\beta $ and $\alpha $ particles emitted are

When $_3Li^7$ nuclei are bombarded by protons, and the resultant nuclei are $_4Be^8$, the emitted particles will be

Assertion : Cobalt $-60$ is useful in cancer therapy.

Reason : Cobalt $-60$ is a source of $\gamma  - $ radiations capable of killing cancerous cells

Given the masses of various atomic particles $m _{ p }=1.0072 u , m _{ n }=1.0087 u$ $m _{ e }=0.000548 u , m _{ v }=0, m _{ d }=2.0141 u$ where $p \equiv$ proton, $n \equiv$ neutron, $e \equiv$ electron, $\overline{ v } \equiv$ antineutrino and $d \equiv$ deuteron. Which of the following process is allowed by momentum and energy conservation $?$