3.5 I can recall the reaction of methane and bromine

   1.    Alkanes react with bromine in the presence of UV light.  Explain why this condition is necessary

UV light is needed to break the bonds between of bromine, because UV light provides the energy to break the bonds.

2.What is this type of reaction called?

Substitution Reaction

3. State and explain the observations

The Brown Bromine slowly looses its color and becomes colorless this is because it is slowly becoming hydrogen Bromide 

5.       Draw the displayed formula of the reaction between methane and bromine (upload a photo)

6.       Write out a balanced (with state symbols) the reaction between ethane and chlorine

C2H6(g) + Cl2(g) -->C2H5Cl(g) +HCl(g)

7.       State and explain the observations in this chemical reaction

The colour changes from a yellow to colourless this is because the chlorine reacts with ethane to form a colourless product, this is a substitution reaction.