Which of the following chemical species is linear, planar as well as polar?

Correct Answer:

(1)Explanation

The structure of HCN is shown below;

The bond angle of HCN is ${180}^0$ . HCN  is linear, planar as well as polar. Hence, option (a) is correct.

Incorrect Answer:

(2)Explanation

$\text{Xe}{\text{F}}_2$ is non-polar. Thus, it is incorrect.

Incorrect Answer:

(3) Explanation

${\text{I}}_3^{-}$ is neither polar nor non-polar. Thus, it is incorrect.

Incorrect Answer:

(4) Explanation

$\text{Xe}{\text{F}}_4$ is square planar as well as non-polar. Thus, it is incorrect.

Therefore, correct option is (1).