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JAMB Chemistry 1979 Question 35

Question 35

Gas Laws

Which of the following statements is true?

  1. A.An increase in the temperature of a given mass of gas increases the number of gas molecules.
  2. B.An increase in the temperature of the gas does not affect the kinetic energy
  3. C.An increase in the pressure of the gas is proportional to the increase in volume
  4. D.A decrease in the pressure of the gas is proportional to the increase in volume at constant temperature
  5. E.A decrease in the pressure of the gas decreases the number of gas molecules present.
Show the answer and explanation

Answer: D (A decrease in the pressure of the gas is proportional to the increase in volume at constant temperature)

Explanation

By Boyle's law, at constant temperature pressure falls as volume rises (PV = constant). The other statements are false: heating raises kinetic energy, and the number of molecules is fixed for a given mass.