Question

Which of the following when mixed will give a solution with pH > 7?

• A. $0.1MHCl+0.2MNaCl$
• B. $100mL$ of $0.2M{H}_{2}S{O}_4$ $+100mL$ of $0.3MNaOH$
• C. $100mL$ of $0.1MC{H}_{3}COOH$ $+100mL$ of $0.1MKOH$
• D. $25mL$ of $0.1MHN{O}_3$ $+25mL$ of $0.1MN{H}_3$

Answer 1

Answer: (C)

$100mL$ of $0.1MC{H}_{3}COOH$ $+100mL$ of $0.1MKOH$

$0.1MHCl+0.2MNaCl$

strong acid + neutral salt

So, $pH<7$

100 mL of 0.2 M $H_{2}S{O}_4$ + 100 mL of 0.3 M $NaOH$

$=2\times 0.2\times 100$ ($\because$ 2 moles of $\left[H^{+}\right]$) $=100\times 0.3$

So, resulting solution will be acidic and $pH<7$.

100 mL of 0.1 M $H{C}_2{H}_3{O}_2$ + 100 mL of 0.1 M $KOH$

weak acid strong base

So, resulting solution will be basic and $pH>7$.

25 mL of 0.1 $HN{O}_3$ + 25 mL of 0.1 M $N{H}_3$

strong acid weak base

So, $pH<7$.

Hence, option C is correct.