What is the purpose from placing
and what is the colour of

question 1) The purpose of placing paraffin oil was to show that it has a high concentration of CO2 in the solution in comparison to yeast fungus + sugary solution which has a very low concentration of CO2.

question 2) I would infer that the color would become green as there is high concentration of CO2 (paraffin oil) going into it raising the overall concentration at the end of the experiment to green.