Transition and InnerTransition Elements - Result Question 61
####62. Consider the following list of reagents, acidified $K _2 Cr _2 O _7$, alkaline $KMnO _4, CuSO _4, H _2 O _2, Cl _2, O _3, FeCl _3, HNO _3$ and $Na _2 S _2 O _3$. The total number of reagents that can oxidise aqueous iodide to iodine is
(2014 Adv.)
Subjective Questions
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Answer:
Correct Answer: 62. (7)
Solution:
- Acidified $K _2 Cr _2 O _7, CuSO _4, H _2 O _2, Cl _2, O _3, FeCl _3$ and $HNO _3$ oxidise aq. iodide to iodine. Alkaline $KMnO _4$ oxidise aq. iodide to $IO _3^{-}$. $Na _2 S _2 O _3$ is a strong reducing agent which on reaction with $I _2$ produces $I^{-}$.
$$ Na _2 S _2 O _3+I _2 \longrightarrow 2 I^{-}+Na _2 S _4 O _6 $$
Therefore, no reaction takes place between $Na _2 S _2 O _3$ and iodide ion.
Hence, correct integer is (7).
