Redox Reactions

Assuming complete ionisation, same moles of which of the following compounds will require the least amount of acidified KMnO4 for complete oxidation?

1. FeSO3
2. FeC2O4
3. Fe(NO2)2
4. FeSO4

Which of the following processes does not involve oxidation of iron?

1. Formation of Fe(CO)5 from Fe.
2. Liberation of H2 from steam by iron at high temperature.
3. Rusting of iron sheets.
4. Decolourisation of blue CuSO4 solution by iron.

The pair of compounds that can exist together is

1. FeCl3, SnCl2
2. HgCl2, SnCl2
3. FeCl2, SnCl2
4. FeCl3, KI

In acidic medium, H2O2 changes Cr2O72- to CrO5 which has two (-O-O-) bonds. Oxidation state of Cr in CrO5 is

1. +5
2. +3
3. +6
4. -10

When Cl2 gas reacts with hot and concentrated sodium hydroxide solution, the oxidation number of chlorine changes from

1. zero to +1 and zero to −5
2. zero to −1 and zero to +5
3. zero to −1 and zero to +3
4. zero to +1 and zero to −3

A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?

1. S
2. H
3. Cl
4. C

In which of the following compounds, nitrogen exhibits highest oxidation state?

1. N2H4
2. NH3
3. N3H
4. NH2OH

Oxidation numbers of P in PO43-, of S in SO42- and that of Cr in Cr2O72- are respectively

1. +3, +6 and +5
2. +5, +3 and +6
3. –3, +6 and +6
4. +5, +6 and +6

Number of moles of MnO4- required to oxidize one mole of ferrous oxalate completely in acidic medium will be

1. 7.5 moles
2. 0.2 moles
3. 0.6 moles
4. 0.4 moles

Which is the best description of the behaviour of bromine in the reaction given below? H2O + Br2 HOBr + HBr

1. Proton acceptor only
2. Both oxidised and reduced
3. Oxidised only
4. Reduced only