Modern Physics Ques 124
- 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 respectively, emitted in this decay process. Which of the following statements is (are) true?
(2018 Adv.)
(a) $N _{\alpha}=5$
(b) $N _{\alpha}=6$
(c) $N _{\beta}=2$
(d) $N _{\beta}=4$
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Answer:
Correct Answer: 124.(a,c)
Solution:
Formula:
- ${ } _{90}^{232} Th$ 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 $2$ .
BETA
