JEE Chemistry 2024 Question with Solution

Given: We need the increasing order of bond angles among $\text{BF}_3$, $\text{PF}_3$, and $\text{CF}_3$.

Find: The correct order of bond angles.

From the solution:

1. $\text{BF}_3$ has $sp^2$ hybridization and a trigonal planar structure, so its bond angle is $120^\circ$.
2. $\text{PF}_3$ has $sp^3$ hybridization with a lone pair and trigonal pyramidal shape, so its bond angle is less than the tetrahedral angle and is approximately $97^\circ$.
3. $\text{CF}_3$ is stated to have the smallest bond angle among these three species in the provided solution.

Thus, the increasing order of bond angles is

Therefore, the correct option is C.

Given: $\text{BF}_3$ is planar, $\text{PF}_3$ is pyramidal with a lone pair, and the provided solution places $\text{CF}_3$ at the smallest bond angle.

Find: Arrange their bond angles in increasing order.

$\text{BF}_3$ has no lone pair on the central atom and adopts trigonal planar geometry, so the bond angle remains $120^\circ$.

$\text{PF}_3$ has one lone pair on phosphorus. Lone pair-bond pair repulsion compresses the bond angle below the ideal tetrahedral value $109.5^\circ$, making it smaller than that of $\text{BF}_3$.

The provided solution further states that $\text{CF}_3$ has the smallest bond angle among the three. Hence,

Therefore, the correct increasing order is $\text{CF}_3 < \text{PF}_3 < \text{BF}_3$, so the answer is C.