Question

An artificial radioactive isotope gave ${}_7^{14}N$ after two successive $\beta -particle$ emissions. The number of neutrons in the parent nucleus must be :

• A. $9$
• B. $14$
• C. $5$
• D. $7$

Answer 1

The correct option is A $9$

The balanced chemical equation for the nuclear transformation is :

${}_a^{b}X{\to }_7^{14}N+2_{-1}^0$.

Mass number of parent nucleus, $b=14$

Atomic number, $a=7-2=5$

The number of neutrons in the parent nucleus ${(}_5^{14}X)$ are $14-5=9$.

Hence, option A is correct.