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 $$H^+$$ ion on its own. It receives $$OH^-$$ ion from water and releases $$H^+$$ ion.
In the light of the above statements, choose the most appropriate answer from the options given below.

We need to evaluate the assertion that boric acid ($$H_3BO_3$$) is a weak acid. Since its acid dissociation constant is $$K_a = 5.8 \times 10^{-10}$$, the assertion is correct.

Reason R states that boric acid cannot release $$H^+$$ directly; instead, it accepts $$OH^-$$ from water and releases $$H^+$$ ion. This is also correct because boric acid acts as a Lewis acid rather than a Bronsted acid.

Next, boric acid reacts with water as follows:

$$B(OH)_3 + H_2O \rightarrow [B(OH)_4]^- + H^+$$

From this reaction, the boron atom in $$B(OH)_3$$, having an empty p-orbital, accepts $$OH^-$$ from water, releasing $$H^+$$ into solution. This indirect mechanism explains why boric acid is weak.

Is R the correct explanation of A?

Yes. The reason that boric acid is weak (Assertion A) is exactly because it cannot release $$H^+$$ on its own and must accept $$OH^-$$ from water (Reason R). This indirect mechanism makes it a weak acid.

Therefore, the correct answer is Option A: Both A and R are correct and R is the correct explanation of A.