Question

In argentometric titration, fluorescein is used as an indicator. This is due to

• A. Adsorption of fluorescein on the surface of AgCl
• B. Absorption of fluorescein by AgCl
• C. Complex formation of fluorescein with \(\mathrm{Ag^+}\)
• D. Oxidation of AgCl to \(\mathrm{AgClO_3}\) \bigskip

Hint:

Fajans method uses \textbf{adsorption indicators}. The colour change occurs due to adsorption of the indicator on the surface of the precipitate at the equivalence point.

Answer 1

The Correct Option is A

Step 1: Fajans method uses adsorption indicator. Fluorescein adsorbs on AgCl surface at endpoint, causing colour change.

Step 2: Write the final answer. \(\boxed{\text{adsorption on the surface of AgCl}.}\)