Question

During adiabatic compression of a gas, its temperature.
A) Falls
B) Rises
C) Remains Constant
D) Becomes zero.

Answer 1

Hint: Adiabatic process is a process that takes place without transferring the heat or the mass in between the system and its surroundings. It transfers the energy to the surroundings only in the form of work.

Complete solution:
Given that the process is adiabatic.
We know that \[\Delta Q = \Delta W + \Delta U\]
Since the process is adiabatic, $\Delta Q = 0$
$ \Rightarrow \Delta U = - \Delta W$
Also, the work done in compressing a gas is negative and hence $\Delta U > 0$
Thus no heat is going out and the work done on the system increases the internal energy and thereby the temperature of the gas also increases.

Thus the correct option is B.

Note: 1. Adiabatic process is a type of thermodynamic process. Adiabatic compression is defined as the compression, in which no heat is added or subtracted from the air. Thus the internal energy of the air is increased which will be equal to the external work done on air. During the process of compression, the pressure of the air will be more than that of the volume of the air.
2. The process that is reversible and also adiabatic is called an adiabatic reversible process. In this process, there is no heat transfer and no entropy change.
3. When zero heat is exchanged with the surroundings, the adiabatic process is reversible. The adiabatic process cannot decrease entropy.
4. Isothermal process is also a thermodynamic process and in this process temperature of the system remains constant and the heat transfer will take place in this process. The adiabatic process will have a temperature change but not the heat transfer.