An indicator 'X' is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with $\mathrm{H}_{2} \mathrm{O}_{2}$ 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

(B) Methyl orange and $\mathrm{H}_{2} \mathrm{O}_{2}$

(C) Starch and $\mathrm{H}_{2} \mathrm{O}_{2}$

JEE Main · 2023 · 29 Jan 2023 · Shift 2 · Chemical Kinetics

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

(A)Starch and iodine✓ Correct
(B)Methyl orange and $H_{2} O_{2}$
(C)Starch and $H_{2} O_{2}$
(D)Methyl orange and iodine

Answer: (A)

Solution

The reaction of iodide ion with hydrogen peroxide liberates iodine into the solution. Iodine gives an intense blue colour with starch through the formation of a starch

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iodine inclusion complex, so starch serves as the indicator and the coloured species it responds to is the iodine that is produced. The indicator and the compound forming the blue complex are therefore starch and iodine.

JEE Main · 2023 · 29 Jan 2023 · Shift 2 · Single correct option

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JEE Main · 2023 · 29 Jan 2023 · Shift 2 · Chemical Kinetics

Solution

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