Question

What is the name of the graph that is drawn, when the temperature is kept constant?

(a) Isotherm

(b) Isochoric and isobar

(c) Isochoric

(d) Isobar

This question was posed to me during an interview for a job.

Enquiry is from States of Matter in portion States of Matter of Chemistry – Class 11

Answer 1

The correct answer is (a) Isotherm.

Explanation:

When the temperature of a gas is kept constant, a graph plotted between pressure and volume is called an isotherm. This refers to the process described by Boyle's Law, where, at constant temperature, the pressure of a gas is inversely proportional to its volume.

• Isotherm (Option a): This represents a curve where temperature is constant.
• Isochoric (Option c): Refers to a process where the volume of the gas remains constant.
• Isobar (Option d): Refers to a process where the pressure remains constant.
• Isochoric and Isobar (Option b): This term combines both isochoric and isobaric processes but is not relevant to the context of constant temperature.

Thus, when you plot pressure versus volume with constant temperature, you get an isotherm.