What is `Delta n` for combustion of 1 mole of benzene, when both the reactants and the products are gas at 298 K?

What happens when (give only balanced equations and write the names of the reactants and products ) Methane reacts with two moles of chlorine gas.

Heat of combustion of benzene is 718 K. cals. When 39 gms of benzene undergoes combustion, the heat liberated is

If a reaction requires two moles of a single reactant to produce one mole of product, what is the ratio of the rate of product formation to the rate of reactant consumption ?