If a gas expands at constant temperature, then (a) K.E. of the molecules is constant (b) K.E. of the molecules decreases (C) K.E. of the molecules increases (d) The pressure of the gas decreases
Answers
Complete step by step solution: In the question it is given that a gas expands at constant temperature.
At constant temperature, pressure of the gas is inversely proportional to volume.
P∝1V
(Boyle’s law).
Coming to given options, option A, Kinetic energy of molecules decreases. It is wrong, because at constant temperature, kinetic energy of the molecules does not change.
Coming to option B, pressure of the gas increases, it is also wrong because if there is no change in temperature of the gas, pressure of the gas is going to decrease.
Coming to option D, the number of molecules of gas increases, it is also wrong because when the temperature is constant the pressure decreases. If pressure decreases there is no change in number of moles of a gas.
Coming to option C, Kinetic energy of molecules remains the same. It is correct because at constant temperature kinetic energy of the gas remains the same.
KE=32RTKE∝T
Therefore, if gas expands at a constant temperature the kinetic energy of the molecules remains the same.
Hence option A is correct
Answer:
(a) K.E. of the molecules is constant.