A student has four samples A, B,C and D containing dil.HCl, aq KCl, dil.NaOH, and distilled water respectively. The solutions with equal pH are:
(a) A and B
(b) B and C
(c) C and D
(d) B and D
The correct answer is d) B and D. Because
A is dil HCl, which is an acid whose pH would be less than 7,
B is aq KCl, which is a neutral salt its pH would be 7,
C is dil NaOH, which is a base hence its pH would be greater than 7,
D is distilled water which is neutral hence pH would be 7.
Therefore among the four samples A, B, C, D ------- B aq KCl and D distilled water will have equal pH.