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JAMB Physics 1997 Question 27

Question 27

Gas Laws

What happens when a gas expands at constant temperature?

  1. A.Its pressure decreases
  2. B.The total momentum of its molecules remains constant
  3. C.Its pressure decreases and the total momentum of its molecules remains constant
  4. D.Its pressure decreases and the total kinetic energy of its molecules decreases
Show the answer and explanation

Answer: A (Its pressure decreases)

Explanation

By Boyle's law, PV is constant at fixed temperature, so a larger volume means a lower pressure. The temperature, and so the kinetic energy of the molecules, stays the same.