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Choose the correct option.
A potassium iodide (KI) solution containing starch turns blue on the addition of chlorine. Which…
A potassium iodide ($\text{KI}$) solution containing starch turns blue on the addition of chlorine. Which one of the following statements explain this?
(P) The reduction potential of $\text{Cl}_2$ is more than that of $\text{I}_2$.
(Q) The oxidation potential of $\text{Cl}_2$ is more than that of $\text{I}_2$.
(R) The product formed when $\text{Cl}_2$ combines with starch is blue.
(S) The product formed when $\text{I}_2$ combines with starch is blue.
- (a)Only P and R
- (b)Only Q and R
- (c)Only Q and S
- (d)Only P and S
Answer
Answer
Correct option: (d)
Answer: (d) Only P and S
Chlorine has the higher reduction potential, so it oxidises $\mathrm{I^-}$ to $\mathrm{I_2}$, and iodine forms a blue complex with starch.