Question

Assertion: The isothermal curves intersect each other at a certain point.
Reason: The isothermal changes take place rapidly, so the thermal curves have very little slope.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

An process is said to be isothermal when there is no change in the temperature of the system or the temperature remains constant throughout the experiment. This can be achieved by insulating the system from the surrounding. Example water kept is a thermos flask which remains hot or cold for a long duration of time.

Formula used:
PV=constant at constant T

Complete step-by-step answer:
Let us consider an ideal gas. Then we can say that an isothermal process is where the system undergoes very slow changes like expansion or compression of the gas to avoid the loss of heat. As they are slow they have steeper slopes when PV graph is potted, where P is the pressure applied on the and V is the volume of the gas at a constant temperature T.
Hence clearly the isothermal process is not rapid. Then clearly the reason is false.
From Boyle’s laws we know that PV is a constant for ideal gases at constant temperature. Hence clearly there cannot be two volumes for the same pressure or two pressures for the same volume. Thus clearly, the curves of the isothermal graph do not intersect.
Thus clearly, the assertion is wrong.
Hence the answer is D. Both Assertion and Reason are incorrect.

So, the correct answer is “Option D”.

Note: From ideal gas law, we know that PV=nRT where P is the pressure applied on the and V is the volume of the gas which contains n number of molecules at temperature T and R is the gas constant. We can vary the different parameters to understand the behaviours of the gas in various conditions.