The correct statement(s) for orthoboric acid is/are
- (A)It behaves as a weak acid in water due to self ionization.
- (B)Acidity of its aqueous solution increases upon addition of ethylene glycol.✓ Correct
- (C)It has a three dimensional structure due to hydrogen bonding.
- (D)It is a weak electrolyte in water.✓ Correct
Answer: (B), (D)
Solution
Orthoboric acid, or :
(A) Self-ionization: Boric acid is a weak Lewis acid, not a Brønsted acid. It accepts OH⁻ from water rather than donating H⁺: . This is not self-ionization. Incorrect.
(B) Ethylene glycol increases acidity: Ethylene glycol forms a stable complex with boric acid, shifting the equilibrium and increasing the release of H⁺ ions, thus increasing acidity. Correct.
(C) 3D structure: Orthoboric acid has a layered 2D structure (not 3D) with hydrogen bonding between layers. Incorrect.
(D) Weak electrolyte: Boric acid ionizes only slightly in water, making it a weak electrolyte. Correct.
Correct answers: (B) and (D).
(A) Self-ionization: Boric acid is a weak Lewis acid, not a Brønsted acid. It accepts OH⁻ from water rather than donating H⁺: . This is not self-ionization. Incorrect.
(B) Ethylene glycol increases acidity: Ethylene glycol forms a stable complex with boric acid, shifting the equilibrium and increasing the release of H⁺ ions, thus increasing acidity. Correct.
(C) 3D structure: Orthoboric acid has a layered 2D structure (not 3D) with hydrogen bonding between layers. Incorrect.
(D) Weak electrolyte: Boric acid ionizes only slightly in water, making it a weak electrolyte. Correct.
Correct answers: (B) and (D).
JEE Advanced · 2014 · 25 May 2014 · Paper 1 · One or more correct options