73) Toluene is nitrated and the resulting product is reduced with tin and hydrochloric acid. The product so obtained is diazotised and then heated with cuprous bromide. The reaction mixture so formed contains:

74) Mesodibromobutane on debromination gives:

75) Octane number can be changed by:

76) A fuel has the same knocking property as a mixture of 70% isooctane (2,2,4−trimethylpentane) and 30% n−heptane by volume. The octane number of the fuel is:

77) To a mixture of conc. HNO₃ and conc. H₂SO₄, benzene was added. This mixture was heated for 30 minutes at 100^oC. The main product is: