Choose correct startement (s) regarding the following reaction. $C r_{2} O_{7}^{2 -} (a q) + 3 S O_{3}^{2 -} (a q .) + 8 H^{+} \to 2 C r^{3 +} (a q) + 3 S O_{4}^{2 -} (a q) + 4 H_{2} O$
1. $C r_{2} O_{7}^{2 -}$ is oxidising agent
2. $S O_{3}^{2 -}$ is reducing agent
3. The oxidation number of per 'S' atom in $S O_{3}^{2 -}$ is increased by two.
4. The oxidation number of per 'Cr' atom in $C r_{2} O_{7}^{2 -}$ is decreased by three.
Correct code is

1.2,3,4

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only 3,4

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only 1,3

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Only 4

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Solution

The correct option is A 1.2,3,4
The given reaction is,
$C r_{2} O_{7}^{2 -} (a q) + 3 S O_{3}^{2 -} (a q) + 8 H^{+} \to 2 C r^{3 +} (a q) + 3 S O_{4}^{2 -} (a q) + 4 H_{2} O$

$C r_{2} O_{7}^{2 -}$ oxidises $S O_{3}^{2 -} t o S O_{4}^{2 -}$ Hence, it acts as an oxidizing agent.

Oppositely, $S O_{3}^{2 -}$ reduces $C r_{2} O_{7}^{2 -}$ to $C r^{3 +}$ . Hence, it acts as a reducing agent.

The oxidation state of $S$ in $S O_{3}^{2 -}$ is $+ 4$ and the oxidation state of $S$ in $S O_{4}^{2 -}$ is $+ 6$ . The oxidation number of each $S$ atom increases from $+ 4$ to 6 Thus, the oxidation number is increased by 2.

The oxidation number of $C r$ in $C r_{2} O_{7}^{2 -}$ is $+ 6$ and the oxidation number of $C r$ in $C r^{3 +}$ is $+ 3$ . The oxidation number of each chromium atom decreases from $+ 6$ to $+ 3$ . Thus, it decreases by 3.

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Similar questions

{C r}_{2} O_{7}^{2 -} (a q) + 3 {S O}_{3}^{2 -} (a q) + 8 H^{+} ⟶ 2 {C r}^{3 +} (a q) + 3 {S O}_{4}^{2 -} (a q) + 4 H_{2} O

C r_{2} O_{7}^{2 -} (a q) + S O_{3}^{2 -} (a q) \to C r^{3 +} (a q) + S O_{4}^{2 -} (a q)

M n O_{4}^{-} (a q .) + 8 H^{+} (a q .) + 5 e^{-} \to M n^{2 +} (a q .) + 4 H_{2} O (l); E^{o} = 1.51 V

C r_{2} O_{7}^{2 -} (a q .) + 14 H^{+} (a q .) + 6 e^{-} \to 2 C r^{3 +} (a q .) + 7 H_{2} O (l); E^{o} = 1.38 V

F e^{3 +} (a q .) + e^{-} \to F e^{2 +} (a q .); E^{o} = 0.77 V

C l_{2} (g) + 2 e^{-} \to 2 C l^{-} (a q .); E^{o} = 1.40 V

F e (N O_{3})_{2}

M n O_{4}^{-} (a q .) + 8 H^{+} (a q .) + 5 e^{-} \to M n^{2 +} (a q .) + 4 H_{2} O (l); E^{\circ} = 1.51 v o l t

C r_{2} O_{7}^{2 -} (a q .) + 14 H^{+} (a q .) + 6 e^{-} \to 2 C r^{3 +} (a q .) + 7 H_{2} O (l)^{'} E^{\circ} = 1.38 v o l t

F e^{3 +} (a q .) + e^{-} \to F e^{2 +} (a q .); E^{\circ} = 0.77 v o l t

C l_{2} (g) + 2 e^{-} \to 2 C l^{-} (a q .); E^{\circ} = 1.40 v o l t

F e (N O_{3})_{2}

M n O_{4}^{-} (a q) + 8 H^{+} (a q) + 5 e^{-} \to M n^{2 +} (a q) + 4 H_{2} O (I); E^{\circ} = 1.51 V

C r_{2} O_{7}^{2 -} (a q) + 14 H^{+} (a q) + 6 e^{-} \to 2 C r^{3 +} (a q) + 7 H_{2} O (I); E^{\circ} = 1.38 V

F e^{3 +} (a q) + e^{-} \to F e^{2 +} (a q); E^{\circ} = 0.77 V

C l_{2} (g) + 2 e^{-} \to 2 C l^{-} (a q); E^{\circ} = 1.40 V

F e (N O_{3})_{2}

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