NEET2016Chemistryp Block Elements (Group 13 & 14)Actual
Assertion : H ₃ BO ₃ is a weak acid. Reason: Water extracts the proton of H ₃ BO ₃ .
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion.
- BIf both assertion and reason are true but reason is not the correct explanation of assertion.
- CIf assertion is true but reason is false.
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false.
Step-by-step solution
H ₃ BO ₃ is a very weak monobasic acid (K_a=5.6 10⁻¹⁰ ) but it does not act as a proton donor. It behaves as a Lewis acid i.e., it accepts a pair of electrons from OH ⁻ ion of H ₂ O . H - OH + B ( OH )₃ [ B ( OH )₄ ]⁻+ H ⁺