The concentration of which ion is decreased when $NH_3$ solution is added?

Identify the conjugate acid-base pairs in the reaction: $NH_{3(aq)} + H_2O_{(l)} \rightleftharpoons NH_{4(aq)}^+ + OH_{(aq)}^-$

The conjugate base of sulphuric acid is

In the reaction $HBr + H_2O \rightleftharpoons H_3O^{+} + Br^{-}$,the conjugate base of the weak acid is .......

If $pK_b$ for fluoride ion $(F^-)$ at $25\,^{\circ}C$ is $10.83$,the ionisation constant $(K_a)$ of hydrofluoric acid $(HF)$ in water at this temperature is:

In which of the following does $HCl$ $NOT$ act as an acid?