Potassium Permanganate
Trending Questions
Q. The reaction of aqueous KMnO4 with H2O2 in acidic conditions gives
- Mn4+ and O2
- Mn2+ and O2
- Mn2+ and O3
- Mn4+ and MnO2
Q. The colour of KMnO4 is due to
- M → L charge transfer transition
- d - d transition
- L → M charge transfer transition
- σ−σ∗ transition
Q. A green solution of potassium manganate (VI) turns purple and a brown solid is precipitated, when CO2 gas is bubbled through the solution.
The purple colour is due to the formation of X, and the brown solid that is precipitated is Y. X and Y respectively are:
The purple colour is due to the formation of X, and the brown solid that is precipitated is Y. X and Y respectively are:
- Manganese dioxide (IV), Potassium permanganate (VIII)
- Potassium permanganate (VII), Manganese dioxide (IV)
- Potassium permanganate (VIII), Manganese oxide (II)
- Manganese oxide (II), Manganese trioxide (III)
Q. In the redox titration using potassium permanganate, the acidification is usually done using H2SO4 instead of HCl. Why?
- H2SO4 is stronger acid than HCl.
- HCl is oxidised by KMnO4 to Cl2.
- H2SO4 is a dibasic acid.
- Only H2SO4 is completely ionised.
Q. Which of the statement is incorrect about potassium permanganate?
- Potassium permanganate is a powerful oxidizing agent
- Potassium permanganate is a violet-black crystalline solid
- Potassium permanganate is stable in acidic medium
- Potassium permanganate can oxidize sulphites to sulphates
Q. Consider an indicator HIn. Find the change in pH i.e. ΔpH of an acidic indicator when the ratio [In−][HIn] changes from 0.2 to 2.
Given KIn=1×10−5
Given KIn=1×10−5
- 1
- 0.1
- 2
- 0.2
Q. A black compound ‘A’ in its solid state is fused with KOH and KClO3. The aqueous extract of the fused mass is a green coloured solution ‘B’. On passing CO2 gas through it, pink colour of ‘C’ is noticed along with some black insoluble mass of ‘A’. The pink coloured solution is decolourised by Fe2+ in acidic medium. The oxidation state of the central metal in ‘C’ is?
- +4
- +5
- +6
- +7
Q. Why is HCl not used to make the medium acidic in oxidation reactions of KMnO4 in acidic medium?
- KMnO4 acts as a reducing agent in the presence of HCl
- KMnO4 is a weaker oxidising agent than HCl
- KMnO4 oxidises HCl into Cl2 which is also an oxidising agent
- Both HCl and KMnO4 act as oxidising agents
Q.
When MnO2 is fused with KOH a coloured compound is formed. The product and its colour are
K2MnO4 Purple green
KMnO4 Purple
Mn2O3 Brown
Mn3O4 Black
Q. The manganate and permanganate ions are tetrahedral, due to:
- The π-bonding which involves the overlap of p-orbitals of oxygen with the d-orbitals of manganese
- There is no π-bonding in both the ions
- The π-bonding which involves the overlap of p-orbitals of oxygen with the p-orbitals of manganese
- The π-bonding which involves the overlap of d-orbitals of oxygen with the d-orbitals of manganese
Q. In a neutral or faintly alkaline solution, 8 moles of permanganate anion quantitatively oxidized thiosulphate anions to produce X moles of a sulphur containing product. The magnitude of X is
Q. Name the gas that can readily decolourise acidified KMnO4 solution.
- SO2
- NO2
- P2O5
- CO2
Q. An acidified solution of KMnO4 oxidizes
- sulphates
- sulphites
- Nitrates
- ferric salts
Q. When KMnO4 solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because:
- CO2 is formed as the product
- The reaction is exothermic
- MnO−4 catalyses the reaction
- Mn2+ acts as an autocatalyst
Q. The LUMO in CO is
- σ−bonding
- π−bonding
- π−antibonding
- σ−antibonding
Q. In the redox titration using potassium permanganate, the acidification is usually done using H2SO4 instead of HCl. Why?
- H2SO4 is stronger acid than HCl.
- HCl is oxidised by KMnO4 to Cl2.
- H2SO4 is a dibasic acid.
- Only H2SO4 is completely ionised.
Q. In a redox reaction, how many moles of electrons are accepted by 1 mole of MnO4 in acidic medium?
- 3
- 5
- 52
- 6
Q. Which of the following is not true about Mn2O7?
- It is acidic in nature
- It is a very good oxidizing agent
- It is a stable anhydride of permanganic acid and is stable at temperatures above 60 ∘C
- Mn has a tetrahedral geometry in Mn2O7
Q. A sodium salt of an organic acid ‘X’ produces effervescence with conc.H2SO4. ‘X’ reacts with the acidified aqueous CaCl2 solution to give a white precipitate which decolourises an acidic solution of KMnO4. ‘X’ is:
- HCOONa
- CH3COONa
- Na2C2O4
- C6H5COONa
Q. The oxidation number of Mn in the product of alkaline oxidative fusion of MnO2 is ___
Q. Which of the following reactions are disproportionation reactions?
- 2MnO4−+3Mn2++2H2O⟶5MnO2+4H+
- 2KMnO4⟶K2MnO4+MnO2+O2
- 3MnO42−+4H+⟶2MnO4−+MnO2+2H2O
- Cu+⟶Cu+2+Cu
Q.
Which of the following methods can be used to synthesize potassium permanganate commercially?
Fusing KOH with MnO2 and heating the mixture in air followed by electrolytic oxidation of the product in basic medium
Heating a fused mixture of KOH, MnO2 and KClO3 followed by electrolytic oxidation of the product from in basic medium
Heating a fused mixture of KOH, MnO2 and KNO3 followed by electrolytic oxidation of the product from in basic medi
Only b and c
All three options – a, b and c are correct
Q. Which of the following compounds has color but not unpaired electrons?
- MnO2
- KMnO4
- K2MnO4
- MnCl2
Q. In neutral medium, KMnO4 acts as a powerful oxidizing agent according to the reaction:
2KMnO4+H2O→2MnO2+2KOH+3(O). The change involves
2KMnO4+H2O→2MnO2+2KOH+3(O). The change involves
- Loss of 3e−
- Increase of 3e−
- Loss of 5e−
- Gain of 5e−
Q. An acidified solution of KMnO4 oxidizes
- sulphates
- sulphites
- Nitrates
- ferric salts
Q. The number of moles of KMnO4 reduced by one mole of KI in alkaline medium is
- 1
- 2
- 5
- 15
Q. Potassium permanganate acts as an oxidising agent in acidic medium. The number of moles of potassium permanganate that will be needed to react with one mole of sulphide ions in acidic solution is
Q. Why is HCl not used to make the medium acidic in oxidation reactions of KMnO4 in acidic medium?
- KMnO4 acts as a reducing agent in the presence of HCl
- KMnO4 is a weaker oxidising agent than HCl
- KMnO4 oxidises HCl into Cl2 which is also an oxidising agent
- Both HCl and KMnO4 act as oxidising agents
Q. Fusion of MnO2 with KOH in presence of O2 produces a salt W. An alkaline solution of W upon electrolytic oxidation yields another salt X. The manganese containing ions present in W and X, respectively, are Y and Z. Correct statement(s) is(are)
- In an aqueous acidic solution, Y undergoes a disproportionation reaction to give Z and MnO2
- In both Y and Z, π - bonding occurs between the p-orbitals of oxygen and the d-orbitals of manganese
- Y is diamagnetic in nature while Z is paramagnetic
- Both Y and Z are coloured and attain a tetrahedral shape
Q. Suppose you are a banana exporter from Kerala. Recently, you acquired a contract that allows you to export your produce into Europe. As a fruit exporter, you realize that your consignment cannot be shipped from Kerala because your variety of banana has a very short shelf life because it releases more ethylene than the other varieties (Ethylene causes fruits to ripen quickly). How do you propose to extend the shelf life of your produce without going bananas?
- Wrap the raw bananas in a thin plastic sheets before packing.
- Secure the consignment in a freezer.
- Pluck the raw bananas earlier than usual.
- Package the dry bananas with traces of potassium permanganate.