When an acidified solution of ferrous ammonium sulphate is treated with KMnO₄ solution, the ion that gets oxidised is:

1. Fe²⁺

2. S${\mathrm{O}}_4^{2-}$

3. N${\mathrm{H}}_4^{+}$

4. Mn${\mathrm{O}}_4^{-}$

 

In the reaction, 

Cr₂${\mathrm{O}}_7^{2-}$ +14H⁺ + 6I^- $\to$2Cr³⁺ + 7H₂O + 3I₂,

Which element is reduced?

1. I

2. O

3. H

4. Cr

2Na₂S₂O₃ + I₂ $\to$ Na₂S₄O₆ + 2NaI,

the oxidation state of sulphur in tha above reaction:

1. Decreases

2. Increases

3. Remain unchanged

4. None of the above

In the aluminothermic process, aluminium acts as:

1. an oxidising agent

2. a flux

3. a reducing agent

4. a solder

Disproportionation reaction(s) among the following is/are represented by -

1. Cl₂ + 2OH^- $\to$ClO^- + Cl^- + H₂O

2. Cu₂O(s) + 2H⁺ $\to$Cu²⁺ + Cu(s) + H₂O

3. 2HCuCl₂ $\underset{\mathrm{water}}{\overset{\mathrm{Dilution} \mathrm{with}}{\to }}$ Cu + Cu²⁺ + 4 Cl^- +  2H⁺

4. All of the above

During a redox change, the oxidant K₂Cr₂O₇ is always reduced to:

1. Cr⁵⁺

2. Cr⁴⁺

3. Cr³⁺

4. Cr²⁺

The reaction, 

3ClO^-(aq)$\to$Cl${\mathrm{O}}_3^{-}$(aq) + 2Cl^-(aq)

is an example of:

1. oxidation reaction

2. reduction reaction

3. disproportionation reaction

4. decomposition reaction

Oxidation state of +1 for phosphorus is found in:

1. H₃PO₃ 

2. H₃PO₄

3. H₃PO₂

4. H₄P₂O₇

Which of the following reactions does not represent a redox change?

1. CaCO₃ $\to$CaO + CO₂

2. 2H₂ + O₂ $\to$2H₂O

3. Na + H₂O $\to$ NaOH + \(\frac{1}{2}\)H₂

4. MnCl₃ $\to$ MnCl₂ + \(\frac{1}{2}\)Cl₂

If H₂S is passed through an acidified K₂Cr₂O₇ solution, the colour of the solution:

a. will remain unchanged

b. will change to deep red

c. will change to dark green

d. will change to dark brown