In a radioactive decay chain reaction, 90 230 Th nucleus decays into Po 84 214 nucleus. The ratio of the…

Let number of $\alpha$ particles are $n_{\alpha }$ and $\beta$ particles are $n_{\beta }$.

Given: ${}_{90}{\mathrm{Th}}^{230}{\to }_{84}{\mathrm{Po}}^{214}+n_{\alpha }\alpha +n_{\beta }\beta$.

Change in mass number is $=230-214=4n_{\alpha }$

$\Rightarrow n_{\alpha }=4$

Number of proton, $n_{\beta }=84-\left(90-2n_a\right)$

$\Rightarrow n_{\beta }=2$

So, the ratio, $\frac{n_{\alpha }}{n_{\beta }}=2$