Verified Solution • 2025–26 Session moderate

QJEEM23Chbebc: JEE Main 2023 Chemistry - Class 12 JEEM23Chbebc Solution: An indicator 'X' is used for studying the effect of variation…

An indicator 'X' is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with H2O2\mathrm{H_2O_2} at room temp. The indicator 'X' forms blue coloured complex with compound 'A' present in the solution. The indicator 'X' and compound 'A' respectively are :

Multiple Choice Options

  • A Methyl orange and H2O2\mathrm{H_2O_2}
  • B Methyl orange and iodine
  • C Starch and H2O2\mathrm{H_2O_2}
  • D Starch and iodine

Step-by-Step Verified Solution

The indicator 'X' is starch, and it forms a blue colored complex with iodine (compound 'A'). Therefore, the correct option is:

Option D: Starch and iodine

In this situation, starch is commonly used as an indicator to detect the presence of iodine because starch forms a deep blue complex with iodine. This color change is visible and helps in monitoring the progress of the reaction involving iodide ions and hydrogen peroxide, which ultimately produces iodine. The blue color indicates the presence of iodine in the solution.

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