Given below are two statements: Assertion A: The H–O–H bond angle in water molecule is 104.5°. Reason R: The lone…
Chemical Bonding · Class 11 · JEE Main Previous Year Question
Given below are two statements:
Assertion A: The H–O–H bond angle in water molecule is 104.5°.
Reason R: The lone pair–lone pair repulsion of electrons is higher than the bond pair–bond pair repulsion.
Choose the correct answer:
- a
A is false but R is true
- b
Both A and R are true, but R is not the correct explanation of A
- c
A is true but R is false
- d✓
Both A and R are true, and R is the correct explanation of A
Both A and R are true, and R is the correct explanation of A
🧠 VSEPR predicts that lone pair–lone pair (LP–LP) repulsion > lone pair–bond pair (LP–BP) repulsion > bond pair–bond pair (BP–BP) repulsion. This hierarchy compresses bond angles whenever lone pairs are present.
Assertion A: H–O–H bond angle = 104.5° → True. (Tetrahedral ideal = 109.5°; 2 lone pairs on O compress the H–O–H angle to 104.5°.)
Reason R: LP–LP repulsion > BP–BP repulsion → True.
Is R the correct explanation of A? Yes. The 2 lone pairs on oxygen push the O–H bonding pairs closer together via stronger repulsion, reducing the H–O–H angle from the ideal 109.5° to 104.5°. R correctly and directly explains why A is true.
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