Question

$25mL$ of $0.2MCa(OH{)}_2$ is neutralised by $10mL$ of $1MHCl$. The $pH$ of resulting solution is:

• A. $1.37$
• B. $9$
• C. $12$
• D. $7$

Answer 1

The correct option is D $7$

Number of millimoles of base $\left(Ca\right(OH{)}_2)=N_1{V}_1=2\times M_1\times V_1=2\times 0.2\times 25=10$
Number of millimoles of acid $\left(HCl\right)=N_2{V}_2$ $=10\times 1=10$
As, number of millimoles of acid $=$ number of millimoles of base
$\therefore$ Acid is completely neutralised by base forming a neutral solution.
$\therefore pH$ of the resulting solution $=7$