S3 Chemistry hw?

In the industrial separation of the gases in the mixture, the mixture is cooled down to -80°c and one gas is collected first. The remaining gases are then liquefied by repeated cooling and compression. The resulting liquid mixture is then separated in a tower.
Table below shows boiling points of the gases present in the mixture.(°c)
Argon:-186
Nitrogen-196
neon-246
oxygen-183
xenon-109
carbon dioxide sublimes at -78
helium -269
krypton - 153

Questions
a which gas is separated out at-80°c? Why?
b After removing the gas in a, state the highest temperature that can liquefy all the remaining gases in the mixture.
c arrange the gas in order in which they would be collected during the separation process in the tower
d Explain how the gases in c are separated?
e another gas X is added to the mixture and it is collected between oxygen and krypton during the separation. Predict the boiling point range of gas X


please help!!!!! Thx a lot!!!