In $NH_3$ and $PH_3$,the common property is

The conjugate base of the strong acid in the reaction $CH_3COOH + HCl \rightleftharpoons Cl^{\Theta} + CH_3COOH_2^{\oplus}$ is:

Considering the following reactions,which pair of reactions shows that water has basic properties?
$(i) \ CO_2 + H_2O \rightleftharpoons H_2CO_3$
$(ii) \ NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^-$
$(iii) \ HCl + H_2O \rightleftharpoons Cl^- + H_3O^+$

The conjugate base of ${(CH_3)_2}\mathop N\limits^ + {H_2}$ is:

Give the classification of acids on the basis of $pK_{a}$ value.

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: