Which of the following is used in conveyor belts?

Ethene is formed when ethanol at $443\, K$ is heated with excess of concentrated sulphuric acid. What is the role of sulphuric acid in this reaction? Write the balanced chemical equation of this reaction.

The oxidising agent which can oxidise ethanol to ethanoic acid is:

What is the molecular formula of methanal?

Write the molecular formula of benzene and state the number of double bonds in its structure.

$(i)$ Give one example with a chemical equation for the following reactions:
$(a)$ Substitution reaction.
$(b)$ Saponification reaction.
$(c)$ Combustion reaction.