Which of the following mixture solution has `pH ~~ 1.0`?

Options

A. `100 mL(M)/(10)HCl +100 mL (M)/(10)NaOH`
B. `55 mL(M)/(10)HCl +45 mL (M)/(10)NaOH`
C. `10 mL(M)/(10)HCl +90 mL (M)/(10)NaOH`
D. `75 mL(M)/(5)HCl +25 mL (M)/(5)NaOH`

Answer

D

Explanation

In choice (D),millimoles of HCl` =75 xx (1)/(5) =15`
Millimoles of NaOH `=25 xx (1)?(5)=5`
Millimoles of HCl left `=15-5 =10`
Volume of solution `=100mL`
`[H_(3)O^(+)]=(10 xx 10^(-3) xx 1000)/(100)M`
`:. pH =-log 10^(-1)=1`