Give the physical and chemical properties of orthoboric acid $(H_3BO_3)$.

(N/A) Physical properties :
$\rightarrow$ Orthoboric acid,$H_3BO_3$,is a white crystalline solid with a soapy touch.
$\rightarrow$ It is sparingly soluble in water but highly soluble in hot water.
$\rightarrow$ It has a layer structure in which planar $BO_3$ units are joined by hydrogen bonds as shown in the figure.
Chemical properties :
$\rightarrow$ It can be prepared by acidifying an aqueous solution of borax :
$Na_2B_4O_7 + 2 HCl + 5 H_2O \rightarrow 2 NaCl + 4 B(OH)_3$
$\rightarrow$ Boric acid is a weak monobasic acid. It is not a protonic acid but acts as a Lewis acid by accepting electrons from a hydroxyl ion :
$B(OH)_3 + 2 HOH \rightarrow [B(OH)_4]^- + H_3O^+$
$\rightarrow$ On heating,orthoboric acid above $370 \ K$ forms metaboric acid,$HBO_2$,which on further heating yields boric oxide,$B_2O_3$ :
$H_3BO_3$ $\xrightarrow{\Delta} HBO_2$ $\xrightarrow{\Delta} B_2O_3$