An indicator is a weak acid and `pH` range of its colour is `3` to `5`. If the neutral point of the indicator lies in the centre of the `[H^(+)]` corresponding to given `pH` range, then `pH` at the equivalence point is

Options

A. `7.0`
B. `4.0`
C. `3.3`
D. `5.0`

Answer

C

Explanation

The neutral point is at the centre of the `H^(+)` ion concentration.
`[H^(+]` at `(pH=3)` is `10^(-3)=100xx10^(-5)`
`[H^(+)]` at `(pH=5)` is `10^(-5)`
Thus, `[H^(+)]` at the centre `=(100xx10^(-5)+10^(-5))/(2)=(101xx10^(-5))/(2)`
`:. pH= -log``((101xx10^(-5))/(2))=3.3`