Question

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

• A. 1.37
• B. 9
• C. 12
• D. 7

Answer 1

Answer: (D)

Number of millimoles of base (i.e., $Ca(OH{)}_2)$

$N_1{V}_1=2\times M_1\times V_1=2\times 0.2\times 25=10$

Number of millimoles of acid (i, e,, $HCl)=N_2{V}_2=10\times 1=10$

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

$\therefore$ Acid is completely neutralised by base forming a neutral solution.

$\therefore pH$ of the resulting solution $=7$