Question

An element $A$ decays into an element $C$ by a two step process
$A \rightarrow B+{ }_{2} He ^{4}$ and $B \rightarrow C+2 e^{-}$. Then,

• A. $A$ and $C$ are isotopes
• B. $A$ and $C$ are isobars
• C. $B$ and $C$ are isotopes
• D. $A$ and $B$ are isobars

Answer 1

Answer: (A)

$z ^{A^{A}} \rightarrow{ }_{Z-2} B^{A-4}+{ }_{2} He ^{4}$
$_{z-2} B^{A-4} \rightarrow{ }_{Z} C^{A-4}+2_{-1} e^{0}$
Hence, $A$ and $C$ are isotopes.