If CrO42- (yellow) changes to Cr2O72- (orange) in pH =x and vice versa in pH=y, then x and y are:

1. 6,8

2. 6,5

3. 8,6

4. 7,7

Subtopic:  Chemistry of Mn and Cr Compounds |
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Identify the oxidation product of \(I^-\) with \(MnO^-_4\) in an alkaline environment:

1. \(IO^-_3\)
2. \(I_2\)
3. \(IO^-\)
4. \(IO^-_4\)
Subtopic:  Chemistry of Mn and Cr Compounds |
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When potassium permanganate \(KMnO_4\) acts as an oxidizing agent, it eventually forms \(\mathrm{MnO}_4^{2-}, \mathrm{MnO}_2, \mathrm{Mn}_2 \mathrm{O}_3 \text { and } \mathrm{Mn}^{2+}\). What are the corresponding number of electrons transferred in each of these cases?
1. 1, 3, 4, 5 2. 3, 2, 1, 4
3. 1, 5, 3, 7 4. 4, 3, 2, 1
Subtopic:  Chemistry of Mn and Cr Compounds |
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In the preparation of KMnO4, pyrolusite (MnO2) is first converted to dark green potassium manganate. In this conversion, the oxidation state of manganese changes from:
1. +1 to +3 2. +2 to +4
3. +3 to +5 4. +4 to +6
Subtopic:  Chemistry of Mn and Cr Compounds |
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What substance is produced when potassium dichromate (K2Cr2O7) is added to ethanol (C2H5OH) in an acidic solution?
1. \(\mathrm{C}_2 \mathrm{H}_6 \) 2. \(\mathrm{CH}_3 \mathrm{COOH} \)
3. \(\mathrm{K}^{+} \mathrm{C}_2 \mathrm{H}_5 \mathrm{O}^{-} \) 4. \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OC}_2 \mathrm{H}_5\)
Subtopic:  Chemistry of Mn and Cr Compounds |
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In the titration of KMnO₄ or its use as an oxidizing agent, the medium is acidified with dilute H₂SO₄ rather than HCl because:

1. Both HCl and  KMnO4 act as oxidising agents
2. KMnO4 oxidises HCl into Cl2, which is also an oxidising agent
3. KMnO4  is a weaker oxidising agent than HCl
4. KMnO4 acts as a reducing agent in the presence of HCl
Subtopic:  Chemistry of Mn and Cr Compounds |
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During the qualitative analysis of SO₃²⁻ using acidified H₂SO₄, SO₂ gas is evolved. This gas turns K₂Cr₂O₇ solution:
1. Green
2. Black
3. Blue
4. Red
Subtopic:  Chemistry of Mn and Cr Compounds |
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The fusion of chromite ore (FeCr2O4) with Na2CO3 in air gives a yellow solution upon the addition of water. Subsequent treatment with H2SO4 produces an orange solution.
The yellow and orange colours, respectively, are due to the formation of:

1. Na2CrO4 and Na2Cr2O7

2. Cr(OH)3 and Na2Cr2O7

3. Cr2(CO3)3 and Fe2(SO4)3

4. Cr(OH)3 and Na2CrO4

Subtopic:  Chemistry of Mn and Cr Compounds |
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Which one of the following statements is correct when SO2 is passed through acidified K2Cr2O7solution?

1. The solution is decolorized.

2. SO2 is reduced.

3. Green coloured Cr2(SO4)3 is formed.

4. The solution turns blue.

Subtopic:  Chemistry of Mn and Cr Compounds |
 80%
Level 1: 80%+
NEET - 2016
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