Explain the nature of boric acid $(H_3BO_3)$ as a Lewis acid in water. The structure of $H_3BO_3$ is given below:
$H-O-B(OH)_2$

(N/A) Boric acid $(H_3BO_3)$ acts as a weak monobasic Lewis acid in water.
It does not release $H^+$ ions directly. Instead,it accepts a lone pair of electrons from an $OH^-$ ion provided by the water molecule to complete its octet.
The reaction is as follows:
$B(OH)_3 + 2H_2O \rightarrow [B(OH)_4]^- + H_3O^+$