Hi Shanice, u need to know that Bromine exists as diatomic molecule, thus the formula is Br2. This will give u the n value of 0.05 mol. U also need to know the equation so that u can deduce the stoichiometric coefficient of alkene.

Qn5). U are already on the right step. U just have to know the meaning of empirical and molecular formula. Empirical formula means the basic formula, while molecular formula = (empirical formula)n. In this case, (CH2)n. Using this formula, u can work out the solution.