Q. A nucleus with $Z = 92$emits the following in a sequence : $\alpha,\alpha,\beta^{-},\beta^{-},\alpha,\alpha,\alpha,\alpha:\beta^{-},\beta^{-},\alpha,\beta^{+},\beta^{+},\alpha.$ The $Z$ of the resulting nucleus is

A) 76
B) 78
C) 82
D) 74
Explanation

(b) Since, 8$\alpha - particles\ \ 4\beta$$^{—}$particles are emitted, and $2\beta$$^{+}$ particles are emitted so new atomic number.
$Z’ = \ Z - 8\ \times \ 2\ + \ 4\ \times 1\ - \ 2 \times 1$
$= 92 - 16\ + \ 4 - 2$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 92 - 14$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 78$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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