JEE MAIN - Chemistry (2022 - 28th July Morning Shift - No. 13)

For kinetic study of the reaction of iodide ion with $$\mathrm{H}_{2} \mathrm{O}_{2}$$ at room temperature :

(A) Always use freshly prepared starch solution.

(B) Always keep the concentration of sodium thiosulphate solution less than that of KI solution.

(D) Record the time immediately before the appearance of blue colour.

(E) Always keep the concentration of sodium thiosulphate solution more than that of KI solution.

Choose the correct answer from the options given below :

$$(\mathrm{A}),(\mathrm{B}),(\mathrm{C})$$ only

$$(\mathrm{A}),(\mathrm{D}),(\mathrm{E})$$ only

$$(\mathrm{D}),(\mathrm{E})$$ only

$$(\mathrm{A}),(\mathrm{B}),(\mathrm{E})$$ only

Explanation

To minimize contamination, use freshly prepared starch solution to determine end point. As $\mathrm{KI}$ is used in excess to consume all the $\mathrm{H}_{2} \mathrm{O}_{2}$ the concentration of sodium thiosulphate solution is less than $\mathrm{KI}$ solution. After appearance of blue colour record the time immediately.

JEE MAIN - Chemistry (2022 - 28th July Morning Shift - No. 13)

Explanation

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