Question

25 mL, 0.2 M Ca(OH)₂ is neutralised by 10 mL of 1 M HCl. Then pH of resulting solution is

(a) 1.37

(b) 9

(c) 12

(d) 7

Answer 1

Correct option  (d) 7

Explanation:

Number of millimoles of base (l.e., Ca(OH)2)

= N₁ V₁ = 2 x M₁ x V₁ = 2 x 0.2 x 25 = 10

Number of millimoles of acid (i.e., HCl) = N₂V₂ =10 x 1=10

As, no. of millimoles of acid= no. of millimoles of base

.'.  Acid is completely neutralised by base forming a neutral solution.

.'. pH of the resulting solution = 7