If $pK_b$ of a base is $5$,then $K_a$ of its conjugate acid will be

Which of the following is not a Lewis base?

Conjugate acid of $NH_2^{-}$ and $NH_3$ are respectively

When hydrogen chloride is dissolved in acetic acid,the following equilibrium is established: $HCl + CH_3COOH \rightleftharpoons Cl^- + CH_3COOH_2^+$. Identify the conjugate acid-base pairs.

Which of the following is both basic and a reducing agent?

Water is a