Question

The molecule in which cations are isoelectric with anions is:

• A. sodium chloride
• B. potassium bromide
• C. lithium fluoride
• D. rubidium bromide

Answer 1

The correct option is D rubidium bromide

When cations and anions have a same number of electrons, they are called isoelectronic.
Rubidium bromide is $RbBr$.
Atomic No. of $Rb$
Electrons in $B{r}^{-}$ is 36. $⟹$ they are isoelectronic.

Sodium chloride is $NaCl$.
Electrons in $N{a}^{+}$ is 10.
Electrons in $C{l}^{-}$ is 18.

Potassium bromide is $KBr$.
Electrons in $K^{+}$ is 18.
Electrons in $B{r}^{-}$ is 36.

Lithium fluoride is $LiF$.
Electrons in $L{i}^{+}$ is 2.
Electrons in $F^{-}$ is 10.