At the end point, there is a sharp change of colour in the indicator. This happened because the

Options

A. `pH` a end point changes sharply.
B. Structure of the indicator changes.
C. Colour of indicator is adsorbed by water.
D. Dissociation constant of acid and base differ by `10.`

Answer

A, B

Explanation

a. Correct: At the point, `[OH^(o+)]` becomes small and to change it, small amount of `[overset(Theta)OH]` is required. When `[H^(o+)]` changes from `10^(-6)M` to `10^(-7)M, pH` change is one, but the volume of `NaOH` required for this change is very small. So the curve changes sharply.
b. Correct: Quinoid structure is obtained.
(c) and (d) are wrong statements.