At `80^(@)C` distilled water has `[H_(3)O^(+)]` concentration equal `[OH^(-)] 1xx10^(-6) "mole"//litre`. The value of `K_(w)` at this temperature will be

Options

A. `1 xx 10^(-6)`
B. `1 xx 10^(-9)`
C. `1 xx 10^(-12)`
D. `1 xx 10^(-15)`

Answer

C

Explanation

`K_(w) = [H_(3)O^(+)][OH^(-)]`
Concentration of `H_(3)O^(+)` in distilled water `= 1 xx 10^(-6)` mol/l.
Now `[H_(3)O^(+)] = [OH^(-)]`
`K_(w) = [1 xx 10^(-6)] xx [1 xx 10^(-6)] = 1 xx 10^(-12)`.