When KMnO4 solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because

1. CO2 is formed as the product.

2. Reaction is exothermic.

3. MnO4– catalyses the reaction.

4. Mn2+ acts as autocatalyst.

Subtopic:  f-Block Elements- Properties & Uses |
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There are 14 elements in actinoid series. Which of the following elements does not belong to this series?

1. U

2. Np

3. Tm

4. Fm

Subtopic:  f-Block Elements- Properties & Uses |
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Identify the amphoteric oxides from the list provided:

Mn2O7, CrO3, Cr2O3, CrO, V2O5, V2O4

1. V2O5, Cr2O3

2. Mn2O7, CrO3

3. CrO, V2O5

4. V2O5, V2O4

Subtopic:  d-Block Elements- Properties & Uses |
 67%
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Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

1. They have high melting points in comparison to pure metals.

2. They are very hard.

3. They retain metallic conductivity.

4. They are chemically very reactive.

Subtopic:  d-Block Elements- Properties & Uses |
 84%
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Which of the following statements does not hold true?

1. Copper liberates hydrogen from acids.
2. In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine.
3. Mn3+ and Co3+ are oxidising agents in aqueous solution.
4. Ti2+ and Cr2+ are reducing agents in aqueous solution.
Subtopic:  Electrochemical Series |
 65%
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The reason for not utilizing HCl to acidify the medium in oxidation reactions involving KMnO4 (in an acidic environment) is:

1. Both HCl and KMnO4 act as oxidizing agents.
2. KMnO4 oxidizes HCl into Cl2 which is also an oxidizing agent.
3. KMnO4 is a weaker oxidizing agent than HCl.
4. KMnO4 acts as a reducing agent in the presence of HCl.
Subtopic:  Chemistry of Mn and Cr Compounds |
 81%
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Which has highest melting point?

1. Cr

2. Fe

3. Cu

4. Mo

Subtopic:  d-Block Elements- Properties & Uses |
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The colour of KMnO4 is due to

1. d – d transition

2. Charge transfer spectra

3. Polarisation of ion

4. p – d transition

Subtopic:  Chemistry of Mn and Cr Compounds |
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Which of the following element does not show a variable oxidation state?

1. Fe

2. Mn

3. Cu

4. Zn

Subtopic:  d-Block Elements- Properties & Uses |
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With F highest stable oxidation state of Mn is-

1. + 6

2. + 4

3. + 7

4. + 3

Subtopic:  d-Block Elements- Properties & Uses |
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