Question

Which has minimum bond angle?

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

Hint:

Drago's rule is a powerful shortcut. When the central atom is from the 3rd period or lower (like P, S, As, Se) and is bonded to a less electronegative atom like Hydrogen, assume no hybridization. The bond angles will be very close to $90^\circ$, making them smaller than any comparable $sp^3$ hybridized molecule from the 2nd period.

Answer 1

The Correct Option is D

Step 1: Use VSEPR Theory
Bond angle depends on:
• Number of lone pairs
• Hybridization
• Repulsion: lp-lp > lp-bp > bp-bp

Step 2: Analyze Each Molecule

(A) NH₃
sp³ with 1 lone pair ⇒ 107°

(B) H₂O
sp³ with 2 lone pairs ⇒ 104.5°

(E) SO₂
sp² with 1 lone pair ⇒ ≈ 119°

(C) PH₃
Due to weak hybridization (Drago’s rule):
Bond angle ≈ 93.5°

(D) H₂S
Less hybridization + 2 lone pairs ⇒ ≈ 92°

Step 3: Compare Values
SO₂ > NH₃ > H₂O > PH₃ > H₂S

Step 4: Final Answer
H₂S