10 mL of a strong acid solution of `pH=2.000` are mixed with 990mL of another strong acid solution of `pH=4.000`. The pH of the resulting solution will be:

Options

A. `4.002`
B. `4.000`
C. `4.200`
D. `3.72`

Answer

D

Explanation

`[H^(+)]` after mixing
`= (10^(-2)xx10+10^(-4)xx990)/(1000)`
`= (0.1+0.0990)/(1000)`
`= (0.1990)/(1000)=1.9xx10^(-4)`,
`:. pH=-4-0.28=3.72`