50 mL of 0.2 M ammonia solution is treated with 25 mL of 0.2 M HCI. If pKb, of ammonia solution is 4.75, the pH of the mixture will be :
pH of two solutions : I. 50 ml of 0.2 M~HCl + 50 ml of 0.2 M HA (Ka=1.0×10−5) and II. 50 ml of 0.2 M HCl + 50 ml of 0.2 M NaA will be respectively