Question

Consider the following processes (treat all gases as ideal).

I. The pressure of 1 mole of oxygen gas is allowed to double at constant temperature.

II. Carbon dioxide is allowed to expand at constant temperature to 10 times its original volume.

III. The temperature of 1 mol of helium is increased 25 degrees C at constant pressure.

IV. Nitrogen gas is compressed at constant temperature to half its original volume.

V. A glass of water loses 100 J of energy in the form of heat.

Which of these processes lead(s) to an increase in entropy?

A) I and IV only B) V only C) III and V only D) II and III only E) I and II only

Answer 1

Option D is the right answer .

Entropy increase in II and III only.

Let see why entropy increase. First of all "Increase in entropy" means "increase in randomness"

When a gas is allowed to expand(II) with the same energy, volume increase and the randomness of the gas particles increase Hence it is an indication of the Increase of Entropy.

At constant Pressure when the temperature increases(III) , volume also increase and the particles are more random than earlier. Hence Increase in entropy.

If you apply the same principle to other cases given above. It is quite opposite.

Hence Option D is the right answer