An indicator ‘ X ’ is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with H 2 O 2 at room temp. The indicator ‘ X ’ forms blue colored complex with compound ‘ A ’ present in the solution. The indicator ‘ X ’ and compound ‘ A ’ respectively are

Step-by-step solution

The reaction between iodide ions and hydrogen peroxide ( H 2 O 2 ) occurs in the acidic medium and can be represented in the following manner: 2 I -   ( aq )   +   H 2 O 2   ( l )   +   2 H +   ( aq )   →   I 2   ( g )   +   2 H 2 O   ( l ) In this reaction, hydrogen peroxide oxidises iodide ions (I - ) to molecular iodine. If a calculated amount of sodium thiosulphate is added in the presence of starch solution as an indicator to the above reac