How many of the following are expected to be monobasic acid?

 ${\mathrm{H}}_2{\mathrm{SO}}_5$ , hypochlorous acid, hyponitrous acid, isohypophosphoric acid, sodium hydrogen carbonate, sodium hydrogen phosphate, hydrochloric acid,${\mathrm{H}}_3{\mathrm{BO}}_3$, sodium hydroxide.

Monobasic acid are the acid in which complete dissociation creates a hydrogen ion (or contains one replaceable hydrogen ion) per molecule of the acid. Here, the monobasic acid from the given molecules are

$\mathrm{HOCl}, {\mathrm{NaHCO}}_3, {\mathrm{Na}}_2{\mathrm{HPO}}_4, \mathrm{HCl}, {\mathrm{H}}_3{\mathrm{BO}}_3$

Thus, the correct answer is 5.