Question

In a radioactive reaction ${}_{92}{X}^{232}{\to }_{82}{X}^{204}$ the number of $\alpha$ -particles emitted is:

• A. 7
• B. 6
• C. 5
• D. 4

Answer 1

Answer: (A)

$\alpha -$ particle is a nucleus of helium atom and its symbol is $2He{}^4.$
When an $\alpha -$ particle is emitted from a nucleus, the resultant nucleus reduces in mass number by 4 link and in atomic number by 2 unit.
Loss in mass number $=232-204=28$
Therefore, number of $\alpha -$ particles emitted
$=\frac{28}{4}$
$=7$