Suppose an empty plastic bottle is sealed tightly at room temperature and then placed in the freezer. After some time the bottle changes shape. The bottle becomes slightly crushed as the volume of the air in it decreases. Why does the volume of the air decrease?

Explanation:

Temperatur is proportional to volume so when temperature drops so does volume

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.