Question

Which one of the following have linear structure?
(I) $I^-_3$
(II) $NO^-_2$
(III) $I^+_3$
(IV) $SO_2$
(V) $N_3^-$

• A. I, II and III
• B. I and V
• C. II, III and IV
• D. All of these

Answer 1

Answer: (A), (B), (C), (D)

$I _{3}^{-}$ ion is made up of $I_{2}$ molecule with an $I ^{-}$ bonded to it by means of a coordinate bond. There are two bond pairs and three lone pairs in the outer shell of central atom. To minimise the repulsive forces the three lone pairs occupy the equatorial positions. The ion is therefore linear in shape with a bond angle of exactly $180^{\circ}$



Similarly, $N _{3}^{-}$ ion is also linear in shape.