JEE Main 2022 · 26 Jul · Shift 2 · Chemistry Q70

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ChemistrySingle correct+4 / -1Question 70 of 90

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Boric acid is a weak acid.

Reason R: Boric acid is not able to release $\mathrm{H^+}$ ion on its own. It receives $\mathrm{OH^-}$ ion from water and releases $\mathrm{H^+}$ ion.

In the light of the above statements, choose the most appropriate answer from the options given below.

Both A and R are correct and R is the correct explanation of A.

Both A and R are correct but R is NOT the correct explanation of A.

A is correct but R is not correct.

A is not correct but R is correct.

Answer and worked solution

Official answer: A

Both correct. $\mathrm{B(OH)_3}$ is a Lewis acid: $\mathrm{B(OH)_3+2H_2O\rightarrow[B(OH)_4]^-+H_3O^+}$ . Accepting $\mathrm{OH^-}$ this way is why it is weak, so R explains A.

(A)

Topics:Group 13 Acids and bases

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JEE Main 2022 · 26 Jul · Shift 2, Chemistry question 70