Which of the following pairs of compounds is isoelectronic and...

(i) ${\text{IBr}}_{2}^{−}$



number of the electron in the valence shell $= 7 + 7 + 7 + 1 = 22$

(ii) ${\text{BeCl}}_{2}$



${sp}^{3} \text{d}$ hybridised (linear).

Number of the electron in the valence shell $= 2 + 7 + 7 = 16$

(iii) ${\text{XeF}}_{2}$



number of electron in valence shell $=8 + 7 + 7 = 22$

(iv) ${\text{TeI}}_{2}$



number of the electron in the valence shell $\text{= 6+7+7=24}$

(v) ${\text{IF}}_{3}$



number of the electron in the valence shell $= 7 + 7 + 7 + 7 = 28$

${\text{IBr}}_{2}^{−}$ and ${\text{XeF}}_{2}$ both are isostructural and isoelectronic.