HBr and HI reduce H₂SO₄, HCl can reduce KMnO₄ and HF can reduce:

1. H₂SO₄

2. K₂Cr₂O₇

3. KMnO₄ 

4. none of these

Sulphurous acid can be used as:

1. Oxidising agent

2. Reducing agent

3. Bleaching agent

4. All of the above

When SO₂ is passed through acidified solution of potassium dichromate, then chromium sulphate is formed. The change in oxidation number of chromium is:

1. +4 to+2 

2. +5 to+3

3. +6 to+3

4. +7 to+2

The reaction involving the transfer of five electrons is -

1. Mn${\mathrm{O}}_4^{-}$ $\to$ Mn²⁺

2. Cr${\mathrm{O}}_4^{2-}$ $\to$Cr³⁺

3. Mn${\mathrm{O}}_4^{-}$ $\to$ MnO₂

4. Cr₂${\mathrm{O}}_7^{2-}$ $\to$2Cr³⁺

In the reaction;

2Ag + 2H₂SO₄ $\to$Ag₂SO₄ + 2H₂O + SO₂, H₂SO₄ acts as:

1. Oxidizing agent

2. Reducing agent

3. Dehydrating agent

4. None of the above

Which of the following shows the highest oxidation number in the combined state?

1. Os

2. Ru

3. Xe

4. All of the above

Equation that does not represent a redox reaction is-

1. BaO₂ + H₂SO₄ $\to$BaSO₄ +  H₂O₂ 

2. 2BaO + O₂ $\to$ 2BaO₂ 

3. 2KClO₃ $\to 2$KCl + 3O₂ 

4. SO₂ + 2H₂S $\to$2H₂O + 3S

In the preparation of chlorine from HCl;  MnO₂ acts as:

1. Reducing agent

2. Oxidising agent

3. Catalytic agent

4. Dehydrating agent

Excess of KI reacts with CuSO₄ solution and then Na₂S₂O₃ solution is added to it. Which of the statement is incorrect in this reaction?

1. Evolved I₂ is reduced

2. CuI₂ is formed

3. Na₂S₂O₃ is oxidised

4. Cu₂I₂ is formed

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