Question

The group of elements formed in the final stage of radioactive changes given below will be:

$\begin{array}{cc}{}_{90}T{h}^{231}& \stackrel{-\alpha }{\to }{}_{88}R{a}^{227}\\ IIIgroup& \end{array}$

• A. group II
• B. group III
• C. group IV
• D. none of these

Answer 1

The correct option is A group II

The element formed in the final stage of radioactive change of ${}_{90}T{h}^{231}$ by alpha decay is ${}_{88}R{a}^{227}$ has electronic configuration $Ra:\left[Rn\right]7s^2$, has valance orbital $s$ with two electrons, therefore it belongs to group $II$.