The species among the following,which can act as an acid and a base is

$HNO_3$ in liquid hydrogen fluoride behaves as:

The solvent which neither accepts a proton nor donates a proton is called:

Which of the following is the strongest base?

Four species are listed below:
$i. \, HCO_3^-$
$ii. \, H_3O^{+}$
$iii. \, HSO_4^-$
$iv. \, HSO_3F$
Which one of the following is the correct sequence of their acid strength?

Which of the following is not a protonic acid?