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${\mathrm{O}}_4^{-}$

 

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

1. Cr⁵⁺

2. Cr⁴⁺

3. Cr³⁺

4. Cr²⁺

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

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 

Which of the following colligative properties is associated with the concentration term 'molarity'?

1. Lowering of vap.pressure

2. Osmotic pressure

3. Depression in freezing point

4. Elevation in boiling point

Among the following, In which iron has the lowest oxidation state?

1. Fe(CO)₅

2. Fe₂O

3. K₄Fe(CN)₆

4. FeSO₄.(NH₄)₂SO₄.6H₂O

Which metal exhibits more than one oxidation states?

1. Na

2. Mg

3. Al

4. Fe

Reaction between acidified K₂Cr₂O₇ and iron (II) ions shown by the equation:

Cr₂${\mathrm{O}}_7^{2-}$(aq) + 6Fe²⁺(aq) +14H⁺(aq)$\to$2Cr³⁺(aq) + 7H₂O(l) + 6Fe³⁺(aq)

The correct statement among the following is -

1. Colour of the solution changes from green to blue

2. Iron (II) ions are reduced 

3. Dichromate ions are reduced 

4. Hydrogen ions are reduced

In the equation,

N${\mathrm{O}}_2^{-}$ +  H₂O $\to$N${\mathrm{O}}_3^{-}$ + 2H⁺ + ne^-

n represents

1. 5

2. 1

3. 2

4. 3