How many litres of water must be added to `1 L` of an aqueous solution of `HCl` with a `pH` of `1` to create an aqueous solution with `pH` of `2`?

Options

A. 0.1 L
B. 0.9 L
C. `2.0 L`
D. `9.0 L`

Answer

D

Explanation

`pH = 1 [H^(+)] = 10^(-1) = 0.1 M`
`pH = 2 [H^(+)] = 10^(-2) = 0.01`
for dilution of HCl `M_(1)V_(1) = M_(2)V_(2)`
`0.1 xx 1 = 0.01 xx V_(2)`
`V_(2) = 10 l t`
Volume of water added = 10 - 1 = 1litre.