List of top Physics Questions on Nuclear Decay

What are the respective numbers of $\alpha$ and $\beta$ particles emitted respectively in the following radioactive decay?
$^{200}_{90}\text{X} \rightarrow ^{168}_{80}\text{Y}$
A radioactive nucleus can decay by two different processes. The half-life for the first process is \(t_1\), and that for the second process is \(t_2\). The effective half-life \(\tau\) of the nucleus is given by:
Match List I with List II
List IList II
(A) Rn22286 → Po21884(III) α particle
(B) Bi21483 → Po21484(I) β− particle
(C) Th23490 → U23492(I) β− particle
(D) Na2211 → Na2210(II) β+ particle