27. Arrange the following in increasing order of pH.

KNO3(aq), CH3COONa(aq), NH4Cl(aq), C6H5COONH4(aq)


(i) KNO3 is a salt of strong acid (HNO3) strong base (KOH), hence its aqueous solution is neutral; pH=7.
(ii) CH3COONa is a salt of weak acid (CH3COOH) and strong base (NaOH), hence, its aqueous solution is basic; pH>7.
(iii) NH4Cl is a salt of strong acid (HCl) and weak base (NH4OH) hence, its aqueous solution is acidic; pH<7.
(iv) C6H5COONH4 is a salt of weak acid, C6H5COOH and weak base, NH4OH. But NH4OH is slightly stronger than C6H5COOH. Hence, pH is slightly>7.
Therefore, increasing order of pH of the given salts is,
NH4Cl<C6H6COONH4<KNO3<CH3COONa