Question

An element $A$ decays into an element $C$ by a two step process
$A\to B+{}_{2}H{e}^4$ and $B\to C+2e^{-}$. 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)

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