Which of the following pairs of compounds is isoelectronic and isostructural?
(1) BeCl_2, XeF₂
(2) Tel_2, XeF₂
(3) ${\mathrm{IBr}}_2^{-}$_, XeF₂
(4) IF₃, XeF₂

The hybridisations of atomic orbitals of nitrogen in ${\mathrm{NO}}_2^{+}, {\mathrm{NO}}_3^{-}$ and ${\mathrm{NH}}_4^{+}$ are

(a) sp, sp³ and sp²               (b) sp², sp³ and sp

(c) sp, sp² and sp³               (d) sp², sp and sp³