Correct Answer - C
Suppose 100 mL of 0.1 M NaOH are mixed with 100 mL Of 0.01 M HCl
100mL of 0.1 M NaOH contain NaOH
`=100xx0.1` mmol = 10 mmol
`100 mL` of 0.01 M HCl contain HCl
`=100xx0.01` mmol = 1 mmol
1 mmol of HCl will neutralize 1 mmol of NaOH
`:.` NaOH left unneutralized in the solution
= 9 mmol
Volume of solution after mixing = 200 mL
`:.` Molarity of NaOH in the final solution
`=(9)/(200) M = 0.045M `
`pOH = -log (0.045) = 1.35`
`pH = 14-1.35 = 12.65`
