Question

Carbon dioxide which is a gas under normal conditions of temperature and pressure can be liquefied by compressing it to 70 atm at ordinary temperature. What happens when pressure is suddenly released?

Answer 1

Hey $CO_2$ is a sublimate substance, so it does not have its liquid state.
According to your question;
Carbon dioxide will feel a sudden rise in its temp. because temp. is inversely proportional to pressure.

Answer 2

Carbon dioxide gas under normal conditions of pressure and temperature can be liquefied by compressing the carbon dioxide to 70 atmospheric pressure at ordinary temperature means it will be changed to a liquid state.

When pressure is suddenly released for this liquefied form of carbon dioxide gas, it will not be completely liquid but some of this gas will evaporate to a gaseous state as pressure is reduced here and at low pressure the liquefy gas will change to its gaseous state.