Discussion Forum



1)

In a radioactive decay chain, $_{90}^{232}Th$ nucleus  decays to $_{82}^{212}Pb$ nucleus. Let  $N_{\alpha}$ and $N_{\beta}$ be the number of $\alpha$ and $\beta$- particles repectively, emitted in this decay process. Which of the following statements is(are) true?


A) $N_{\alpha}=5$

B) $N_{\alpha}=6$

C) $N_{\beta}=2$

D) $N_{\beta}=4$

Answer:

Option A,C

Explanation:

 $_{90}^{232}Th$  is converting into $_{82}^{212}Pb$ .

   Change in mass number (A)=20

$\therefore$     Number of $\alpha$ -particle emitted = $\frac{20}{4}=5$

Due to 5 $\alpha$ -particles, Z will change by 10  units.

  Since, given change is 8, therefore number of $\beta$ -particles emitted is 2