Which of the following statement is true with respect to \(\mathrm{H}_{2} \mathrm{O}, \mathrm{NH}_{3}\) and \(\mathrm{CH}_{4}\) ? A. The central atoms of all the molecules are \(\mathrm{sp}^{3}\) hybridized. B. The \(\mathrm{H}-\mathrm{O}-\mathrm{H}, \mathrm{H}-\mathrm{N}-\mathrm{H}\) and \(\mathrm{H}-\mathrm{C}-\mathrm{H}\) angles in the above molecules are \(104.5^{\circ}, 107.5^{\circ}\) and \(109.5^{\circ}\) respectively. C. The increasing order of dipole moment is \(\mathrm{CH}_{4}<\mathrm{NH}_{3}<\mathrm{H}_{2} \mathrm{O}\). D. Both \(\mathrm{H}_{2} \mathrm{O}\) and \(\mathrm{NH}_{3}\) are Lewis acids and \(\mathrm{CH}_{4}\) is a Lewis base E. A solution of \(\mathrm{NH}_{3}\) in \(\mathrm{H}_{2} \mathrm{O}\) is basic. In this solution \(\mathrm{NH}_{3}\) and \(\mathrm{H}_{2} \mathrm{O}\) act as Lowry-Bronsted acid and base respectively. Choose the correct answer from the options given below :

Chemical Bonding and Molecular Structure — JEE Main · 2025 · 24 Jan 2025 · Shift 1 Question with Solution

Which of the following statement is true with respect to

H_{2} O, NH_{3}

and

CH_{4}

?
A. The central atoms of all the molecules are

sp^{3}

hybridized.
B. The

H - O - H, H - N - H

and

H - C - H

angles in the above molecules are

104. 5^{\circ}, 107. 5^{\circ}

and

109. 5^{\circ}

respectively.
C. The increasing order of dipole moment is

CH_{4} < NH_{3} < H_{2} O

.
D. Both

H_{2} O

and

NH_{3}

are Lewis acids and

CH_{4}

is a Lewis base
E. A solution of

NH_{3}

H_{2} O

is basic. In this solution

NH_{3}

and

H_{2} O

act as Lowry-Bronsted acid and base respectively.

Choose the correct answer from the options given below :

(A)A, B and C only✓ Correct
(B)C, D and E only
(C)A, D and E only
(D)A, B, C and E only

Answer: (A)

Solution

Examine each statement.

A. In

H_{2} O

N H_{3}

and

C H_{4}

the central atom (O, N, C) each has four electron domains (bond pairs plus lone pairs) around it, so all three are

s p^{3}

hybridized — true.

B. Lone-pair–bond-pair repulsion exceeds bond-pair–bond-pair repulsion, so the bond angle shrinks as the number of lone pairs increases:

H_{2} O

(two lone pairs) has the smallest angle, close to

104. 5^{\circ}

;

N H_{3}

(one lone pair) is intermediate, close to

10 7^{\circ}

;

C H_{4}

(no lone pair) keeps the ideal tetrahedral angle of

109. 5^{\circ}

— true.

C. Dipole moment increases with bond polarity and lone-pair contribution:

C H_{4}

is non-polar by symmetry,

N H_{3}

has one lone pair reinforcing a net dipole, and

H_{2} O

, with two lone pairs and the more electronegative central atom, has the largest dipole moment — so

C H_{4} < N H_{3} < H_{2} O

— true.

D. A Lewis acid accepts an electron pair;

H_{2} O

and

N H_{3}

both carry lone pairs and act as Lewis bases (electron-pair donors), not acids — false.

E. In aqueous ammonia,

N H_{3} + H_{2} O ⇌ N H_{4}^{+} + O H^{-}

N H_{3}

accepts a proton and is the Lowry–Brønsted base, while

H_{2} O

donates one and is the acid — the roles named in the statement are reversed, so it is false.

Statements A, B and C are correct.

JEE Main · 2025 · 24 Jan 2025 · Shift 1 · Single correct option

JEE Main · 2025 · 24 Jan 2025 · Shift 1 · Chemical Bonding and Molecular Structure

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