Question

Which of the following has the highest bond angle?

• A. ${\mathrm{H}}_2\mathrm{O}$
• B. ${\mathrm{H}}_2\mathrm{S}$
• C. ${\mathrm{NH}}_3$
• D. ${\mathrm{PH}}_3$

Answer 1

The correct option is C

${\mathrm{NH}}_3$

The explanation for the correct answer

(C) ${\mathbf{NH}}_{\mathbf{3}}$

• The angle between two covalent bonds that originate from the same atom is called the Bond angle.
• The Bond angle decreases down the group.
• ${\mathrm{NH}}_3$have $3$bonding pair and $1$lone pair. $\mathrm{N}$is more electronegative, $\mathrm{N}$attracts the shared pair of electrons.
• It experiences a strong repulsion due to electron-electron repulsion force.
• So, ${\mathrm{NH}}_3$has the highest bond angle.

Hence, Option (C) ${\mathbf{NH}}_{\mathbf{3}}$is correct.

The explanation for the incorrect answer

(A) ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$

• Bond angle decreases down the group
• Thus, ${\mathrm{H}}_2\mathrm{O}$ has a greater bond angle than ${\mathrm{H}}_2\mathrm{S}$
• The lone pair-lone pair repulsion on oxygen is more effective.
• Hence, ${\mathrm{H}}_2\mathrm{O}$ has a lesser bond angle than${\mathrm{NH}}_3$.

(B) ${\mathbf{H}}_{\mathbf{2}}\mathbf{S}$

• Bond angle decreases down the group
• Thus, ${\mathrm{H}}_2\mathrm{S}$ has a lesser bond angle than ${\mathrm{H}}_2\mathrm{O}$

(D) ${\mathbf{PH}}_{\mathbf{3}}$

• $\mathrm{P}$is less electronegative than $\mathrm{N}$
• It cannot attract shared pair of electrons effectively.
• So ${\mathrm{PH}}_3$has a lesser bond angle than ${\mathrm{NH}}_3$

Therefore, Option (C) ${\mathbf{NH}}_{\mathbf{3}}$is correct.