The total number of $\alpha$ and $\beta$ particles emitted in the nuclear reaction ${ }_{92}^{238} U \rightarrow{ }_{82}^{214} Pb$ is

The intensity of gamma radiation from a given source is $I$. On passing through $36 \, mm$ of lead,it is reduced to $\frac{I}{8}$. The thickness of lead which will reduce the intensity to $\frac{I}{2}$ will be......$mm$

Assertion: Radioactive nuclei emit $\beta^-$ particles.
Reason: Electrons exist inside the nucleus.

$A$ radioactive decay chain starts from $_{93}Np^{237}$ and produces $_{90}Th^{229}$ by successive emissions. The emitted particles can be:

$A$ 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

The particles emitted in the decay of $ { }_{92}^{238} U $ to $ { }_{92}^{234} U $ are: