Nuclei - Result Question 96

99. An element $A$ decays into element $C$ by a two step process

$A \to B+ _2 He^{4}$

$B \to C+2 e^{-}$

Then

[1989]

(a) $A$ and $C$ are isotopes

(b) $A$ and $C$ are isobars

(c) $A$ and $B$ are isotopes

(d) $A$ and $B$ are isobars

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Answer:

Correct Answer: 99. (a)

Solution:

  1. (a) From eqn. (ii), B has 2 units of charge more than C.

From eqn. (i), $A$ loses 2 units of charge by emission of alpha particle. Hence,

$A$ and $C$ are isotopes as their charge numbers are same.