Question

Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends she got confused. Help her identify the correct set of conditions.
A. Low temperature, low pressure
B. High temperature, low pressure
C. Low temperature, high pressure
D. High temperature, high pressure

Answer 1

Hint: As we have learnt that our atmosphere consists of a mixture of gases like Carbon Dioxide, Oxygen, Nitrogen, etc. The volume and shape of gases is not fixed and they exert equal pressure in all directions. The volume of gases depends upon the amount of gas taken, temperature and pressure applied on it. Gasses have a good amount of space between its particles.

Complete step by step answer:
1. Gases have a fine amount of space between its particles and have no fixed volume or shape but they take up the shape and volume of the container and exert pressure equally in all the directions. They have high compressibility and high expansibility.
2. These identical physical properties of gases make their study easier than solids and liquids.
3. The liquefaction of gases can be done by cooling and compressing them.
4. When the temperature of the gas is decreased, the kinetic energy of the molecules decreases, which results in decreasing the volume of gas making the molecules come much closer to each other and ultimately converting the gaseous state into liquid state.
5. When the pressure is applied or say increased on the gas, it brings the gaseous molecules close to each other which changes the gaseous state into the liquid state. But when a gas is compressed, it results in the production of heat that needs to be cooled down, which can be done by lowering the temperature.
6. Thus, the two specific conditions which can be applied to liquefy the gas are- low temperature and high pressure.

Therefore, the correct answer is option (C).

Note:
Students get confused in the options while sitting in exams, the easiest way to learn these two conditions is thinking of a practical approach like when you cool or compress or put pressure on something it becomes a bit hard. Also, there is a certain temperature above which a gas cannot be liquefied even if high pressure is applied, thus making the effect of temperature a critical phenomenon.