Question

The bond angle in $NF _{3}\left(102.3^{\circ}\right)$ is smaller than $NH _{3} (107.2 \left.^{\circ}\right)$. This is because of

• A. large size of F compared to H
• B. large size of N compared to F
• C. opposite polarity of N in the two molecules
• D. small size of H compared to N

Answer 1

Answer: (C)

opposite polarity of N in the two molecules

Answer 2

In $NF _{3}, N$ is less electronegative as compared to $F$ but in $NH _{3}$, it is more electronegative than $H$. And in case of same central atom, as the electronegativity of other atoms increases, bond angle decreases. Thus, bond angle in $NF _{3}$ is smaller than that in $NH _{3}$ because of the difference in the polarity of $N$ in these molecules.