In one litre of water `10^(-10)` moles of HCl were added. The pH of the solution will be approximately .

Options

A. 7
B. 14
C. 10
D. 4

Answer

A

Explanation

Molar conc. Of HCl`=10^(-10)M`
`[H_(3)O^(+)]` ion already present in water `=10^(-7)M`
Net `[H_(3)O^(+)]=(10^(-7)+10^(-10))`
`=10^(-7) (1+10^(-3))=1.001 xx 10^(-7)`
`pH =-log (1.001 xx 10^(-7))= 7- log 1.001 ~~7`