Redox reaction among the following is -

1. NaCl + KNO₃ $\to$NaNO₃ + KCl

2. CaC₂O₄ + 2HCl $\to$CaCl₂ + H₂C₂O₄

3. Mg(OH)₂ + 2NH₄Cl $\to$MgCl₂ + 2NH₄OH

4. Zn + 2AgCN $\to$2Ag + Zn(CN)₂

Which metal exhibits more than one oxidation states?

1. Na

2. Mg

3. Al

4. Fe

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

In 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

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 

4P + 3KOH + 3H₂O $\to$ 3KH₂PO₂ + PH₃:

Correct statement regarding the above reaction is -

1. P oxidised only

2. P is reduced only

3. P is oxidised as well as reduced

4. None of the above

In the reaction;

3Br₂ + 6C${\mathrm{O}}_3^{2-}$ + 3H₂O $\to$5Br^- + Br${\mathrm{O}}_3^{-}$ + 6HC${\mathrm{O}}_3^{-}$

which statement is correct?

1. Br₂ is oxidised

2. Br₂ is reduced

3. Br₂ is neither oxidised nor reduced

4. Br₂ is oxidised and reduced as well