Question

Which of the following solution will have pH close to 1.0?

• A. 100 mL of (M/10) HCl + 100 mL of (M/10) NaOH
• B. 55 mL of (M/10) HCl + 45 mL of (M/10) NaOH
• C. 10 mL of (M/10) HCl + 90 mL of (M/10) NaOH
• D. 75 mL of (M/10) HCl + 25 mL of (M/10) NaOH

Answer 1

The correct option is D 75 mL of (M/10) HCl + 25 mL of (M/10) NaOH

As we know, $pH=-log\left[H^{+}\right]$

$75mL$ of $\left(M/10\right)HCl+25mL$ of $\left(M/10\right)NaOH$

$\left[H^{+}\right]=\frac{1}{100}(\frac{75}{10}-\frac{25}{10})=\frac{5}{100}$

So, $pH=-log\frac{5}{100}=2-log5=2-0.698=1.3$