Charles’ law – volume–temperature relation at constant pressure According to Charles’ law, the volume of a given mass of a perfect gas varies how with its absolute temperature when the absolute pressure remains constant?

Introduction / Context:
Charles’ law is one of the classical gas laws, explaining how volume depends on temperature when pressure is held constant. It is foundational for understanding thermal expansion of gases and calibrating constant-pressure thermometers.

Given Data / Assumptions:

• Fixed mass of an ideal (perfect) gas.
• Constant absolute pressure.
• Temperature measured on an absolute scale (K).

Concept / Approach:

The ideal-gas equation p * V = n * R * T reduces at constant p and n to V ∝ T. Thus if absolute temperature doubles, volume doubles; if temperature decreases, volume decreases in the same proportion. This direct proportionality is Charles’ law.

Step-by-Step Solution:

Verification / Alternative check:

Experimental plots of V versus T at constant p produce straight lines extrapolating toward V → 0 near T → 0 K, consistent with the law.

Why Other Options Are Wrong:

Indirect, exponential, logarithmic, or independent relations do not follow from the ideal-gas law under the stated constraint.

Common Pitfalls:

Using Celsius instead of Kelvin; direct proportionality is valid only with absolute temperature. Near condensation or very high pressures, real gases deviate, but the ideal relation remains a good model over modest ranges.

Final Answer:

directly