The substance added to SO₃ to manufacture H₂SO₄ by contact process is :

1. H₂O
2. H₂SO₄
3. H₂S₂O₇
4. H₂S

The role of sulphuric acid in the reaction given below is :

S + 2H₂SO₄ ⟶ 3SO₂ + 2H₂O

1. Non volatile acid
2. Oxidising agent
3. Dehydrating agent
4. None of the above

On adding conc. H₂SO₄ to cane sugar, the colour observed is :

1. yellow
2. black
3. green
4. violet

The acid which produces charcoal from sugar is :

1. conc. HNO₃
2. conc. HCl
3. Conc. H₂SO₄
4. conc. H₃PO₄