What is the pH of resulting solution when equal volumes of 0.1(M) NaOH and 0.01(M) HCl are mixed-

Options

A. 12.65
B. 2
C. 7
D. 1.04

Explanation

If V mL 0.1(M) NaOH solution is mixed with VmL 0.01(M) HCl solution, then in the mixed solution,
`[NaOH]=(0.1)/(2)=0.05(M)&[HCl]=(0.01)/2=0.005(M)`
As the concentration of NaOH is higher than that of HCl, HCl reacts completely. The concentration of NaOH left in the solution
= 0.05 - 0.005 = 0.045(M) . or `[OH^-]=0.045(M)" or "pOH=-log(0.045)=1.35`
`:.pH=14-pOH=14-1.35=12.65`