If you spill a chemical toilet cleaning liquid on your hand,what would be your first aid?

Which of the following species acts as both Bronsted acid and base?

Given,$HF + H_2O \rightleftharpoons H_3O^{+} + F^{-}; K_a$
$F^{-} + H_2O \rightleftharpoons HF + OH^{-}; K_b$
Which relation is correct?

The conjugate base of sulphuric acid is

The species: $H_{2}O$,$HCO_{3}^{-}$,$HSO_{4}^{-}$,and $NH_{3}$ can act both as Bronsted acids and bases. For each case,give the corresponding conjugate acid and base.

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R:$
Assertion $A :$ The amphoteric nature of water is explained by using Lewis acid/base concept.
Reason $R :$ Water acts as an acid with $NH_{3}$ and as a base with $H_{2}S$.
In the light of the above statements,choose the correct answer from the options given below: