Question

The group of element formed in the final stage of radioactive change,$\begin{array}{cc}{}_{91}{X}^{231}& \stackrel{-\alpha }{\to }{}_{89}A{c}^{227}\\ & \end{array}$ :

• A. group IV
• B. group V
• C. group II
• D. group III

Answer 1

Answer: (D)

group III

The group of elements formed in the final stage of radioactive changes given below will be Group III.

$\begin{array}{cc}{}_{91}P{a}^{231}& \stackrel{-\alpha }{\to }{}_{89}A{c}^{227}\end{array}$

${}_{89}A{c}^{227}$ is in the III rd group.

The third group contains elements having atomic numbers $89-103$.

During the reaction, an alpha particle is lost which decreases the atomic number by 2 units from 91 to 89 and decreases the mass number by 4 units from 231 to 227.