Question

$20mL$ of $0.1N$ $HCl$ is mixed with $20mL$ of $0.1N$ $KOI$ solution; the pH of the solution will be:

• A. $0$
• B. $2$
• C. $7$
• D. $9$

Answer 1

Answer: (C)

$7$

When you mix strong acid and strong base they react till one of the reagents runs out. What is left is responsible for pH.

Reaction taking place in the solution

$KOH+HCl\rightleftharpoons KCl+H_{2}O$

there are $20\times 0.1=2mmol$ of KOH and $20\times 0.1=2mmol$ of HCl. Since they react 1:1, so after the reaction , nothing will be left as they neutralize each other and thus $pH$ becomes 7.