Redox Reactions · Question 16

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

The oxidation states of sulphur in the anions SO32-, S2O42- and S2O62- follow the order

1. S2O42- < SO32- < S2O62-
2. SO32- < S2O42- < S2O62-
3. S2O42- < S2O62- < SO32-
4. S2O62- < S2O42- < SO32-

Which reaction is not feasible?

1. 2KI + Br2 2KBr + I2
2. 2KBr + I2 2KI + Br2
3. 2KBr + Cl2 2KCl + Br2
4. 2H2O + 2F2 4HF + O2

Oxidation numbers of A, B, C are +2, +5 and -2 respectively. Possible formula of compound is

1. A2(BC2)2
2. A3(BC4)2
3. A2(BC3)2
4. A3(B2C)2