Question

Atomic mass number of an element is 232 and its atomic number is 90. The end products of this radioactive element is an isotope of lead (Atomic mass 208 and atomic number 82). The number of $\alpha\,and\,\beta$-particle emitted is

• A. $\alpha=3,\beta=3$
• B. $\alpha=6,\beta=4$
• C. $\alpha=6,\beta=0$
• D. $\alpha=4,\beta=6$

Answer 1

Answer: (B)

$\alpha=6,\beta=4$

Answer 2

Change in A = 24, hence 6 $\alpha$-particles are emitted. Change in Z = 8 = 6 $\times$ 2-4 $\times$ 1. That is 4 $\beta$-particles are emitted.