Question

In a radioactive decay, an element ${}_Z{X}^A$ emits four $\alpha$-particles, three $\beta$-particles and eight gamma photons. The atomic number and mass number of the resulting final nucleus are

• A. $Z-11,A-16$
• B. $Z-5,A-13$
• C. $Z-5,A-16$
• D. $Z-8,A-13$

Answer 1

Answer: (C)

$Z-5,A-16$

Alpha and beta particles are ${}_{2}H{e}^2$ and ${}_{-1}{e}^0$, respectively.

Whereas atomic number as well as mass number of gamma photon is zero.

Thus nuclear reaction : ${}_Z{X}^A\to$ ${}_{Z-5}{Y}^{A-16}+4$ ${}_{2}H{e}^4+3$ ${}_{-1}{e}^0+8$ $\gamma$

$⟹$ Atomic number of final nucleus is $Z-5$

Also mass number of final nucleus is $A-16$