Physics Thermodynamics UHS 2022
PMDC Verified Question 32 of 54
When a gas is compressed isothermally, the product of its pressure and volume during the process is:
A
Proportional to entropy
B
Constant
C
Zero
D
Not constant
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Constant
1. Concept:

According to Boyle's Law, for a fixed mass of an ideal gas kept at a steady temperature, the pressure is inversely proportional to the volume.

2. Formula:

$$PV = \text{constant}$$

3. Solution:

  • An isothermal compression means temperature \(T\) remains completely unchanged.


  • Based on the ideal gas law \(PV = nRT\), since \(n\), \(R\), and \(T\) are all constants, their product \(nRT\) must be a constant.


  • Consequently, the product of pressure and volume (\(PV\)) remains constant throughout the entire compression.


4. Why other options are incorrect:

The product cannot be zero because matter exists (P, V > 0). It is strictly constant as dictated by the ideal gas equation, not variable.

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