Heat is given to an ideal gas in an isothermal process
A Internal energy of the gas will decrease
B Internal energy of the gas will increase
C Internal energy of the gas will not change
D The gas will do positive work E The gas will do negative work
Choose the correct answer from the options given below:

Question

A force of 10 N is applied to move a body of mass 5 kg over a distance of 3 meters. Find the work done by the force.

Answer 1

To address the question, let's analyze the concepts of an isothermal process in an ideal gas and the associated internal energy changes and work done:

Isothermal Process: An isothermal process occurs at a constant temperature. For an ideal gas, the internal energy U is solely a function of temperature. Therefore, during an isothermal process, the internal energy of the gas remains unchanged as the temperature remains constant.
Internal Energy: As the temperature does not change in an isothermal process, the internal energy of the gas remains constant. This rules out options A and B, which imply changes in internal energy.
Work Done by the Gas: During an isothermal expansion, heat added to the system is used to do work on the surroundings, as the added heat increases the volume while keeping the temperature constant. Thus, the gas performs positive work.

Based on these explanations, let's evaluate the given options:

Option A (Internal energy decreases) and E (Gas does negative work): Both are incorrect since the internal energy does not change, and the gas does positive work in an isothermal process.
Option B (Internal energy increases) and D (Gas does positive work): Internal energy does not increase, ruling this option out.
Option C (Internal energy does not change) and D (Gas does positive work): This is correct, as explained above.
Option C (Internal energy does not change) and E (Gas does negative work): This option is partially correct regarding internal energy but incorrect with respect to work done.

Thus, the correct answer is C and D only:

Internal energy of the gas will not change (C).
The gas will do positive work (D).

Answer 2

To address the question, let's analyze the concepts of an isothermal process in an ideal gas and the associated internal energy changes and work done:

Isothermal Process: An isothermal process occurs at a constant temperature. For an ideal gas, the internal energy U is solely a function of temperature. Therefore, during an isothermal process, the internal energy of the gas remains unchanged as the temperature remains constant.
Internal Energy: As the temperature does not change in an isothermal process, the internal energy of the gas remains constant. This rules out options A and B, which imply changes in internal energy.
Work Done by the Gas: During an isothermal expansion, heat added to the system is used to do work on the surroundings, as the added heat increases the volume while keeping the temperature constant. Thus, the gas performs positive work.

Based on these explanations, let's evaluate the given options:

Option A (Internal energy decreases) and E (Gas does negative work): Both are incorrect since the internal energy does not change, and the gas does positive work in an isothermal process.
Option B (Internal energy increases) and D (Gas does positive work): Internal energy does not increase, ruling this option out.
Option C (Internal energy does not change) and D (Gas does positive work): This is correct, as explained above.
Option C (Internal energy does not change) and E (Gas does negative work): This option is partially correct regarding internal energy but incorrect with respect to work done.

Thus, the correct answer is C and D only:

Internal energy of the gas will not change (C).
The gas will do positive work (D).

The Correct Option is A

Solution and Explanation

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