Question

A nucleus ${}_Z^{A}X$ emits an $\alpha$-particle. The resultant nucleus emit a ${\beta }^{+}$ particle. The respective atomic and mass numbers of the final nucleus will be

• A. $Z-3,A-4$
• B. $Z-1,A-4$
• C. $Z-2,A-4$
• D. $Z,A-2$

Answer 1

Answer: (A)

$Z-3,A-4$

After alpha emission Mass number decreases by $4$, atomic number decreases by $2$.
${}_Z^{A}X⟶{}_{Z-2}^{A-4}Y+\alpha$

After ${\beta }^{+}$ emission
${}_{Z-2}^{A-4}Y⟶{}_{Z-3}^{A-4}Z+{\beta }^{+}$

Hence, Answer is: $A-4,Z-3$