Question

${}_{89}A{c}^{231}$ gives ${}_{82}P{b}^{207}$ after emission of some $\alpha$ and $\beta$ -particles. The number of such $\alpha$ and $\beta$ -particles are respectively:

• A. 5, 6
• B. 6, 5
• C. 7, 5
• D. 5, 7

Answer 1

The correct option is B 6, 5

Number of $\alpha$-particles $=\frac{231-207}{4}=6$.

Number of $\beta$-particles $=89-82-2\times 6=5$.