I did a chocolate lab. It was melting chocolate. These are the tree question please answer all. Please help me ASAP

Which change to the system wood cause the freely-moving piston to lower?

4.25g sample of solid ammonium nitrate dissolves in 60.0g of water in a coffee-cup calorimeter, the temperature drops from 22.0 c to 16.9 c. assume that the specific heat of the solution is the same as that of pure water. calculate delta(h) (in kj/mol nh4no3) for the solution proces.

Which scientists contributed to the determination of how cfcs in clouds in the upper atmosphere could destroy ozone molecules