Question

The combination of plots which does not represent isothermal expansion of an ideal gas is:

• (A) and (C)
• (A) and (D)
• (B) and (D)
• (B) and (C)

Answer 1

The Correct Option is C

To determine which plots do not represent isothermal expansion of an ideal gas, we first need to understand what happens during this process. Isothermal expansion refers to the expansion of a gas at a constant temperature. According to the ideal gas law, PV = nRT. For an isothermal process, where the temperature is constant, this relationship can be rearranged to P = \frac{nRT}{V}, indicating an inverse relationship between pressure and volume, meaning the plot should be a hyperbola when Pressure versus Volume is plotted.

We must evaluate which pair of plots among the options does not satisfy this criterion:

1. Plot (A): This plot must depict an inverse relationship between Pressure and Volume.
2. Plot (B): This plot could be incorrectly depicting a direct linear relationship, which would not represent an isothermal process.
3. Plot (C): This plot could correctly depict a hyperbolic curve corresponding to PV = const.
4. Plot (D): This plot might depict a horizontal line indicating constant pressure, which is characteristic of an isobaric process, not isothermal.

Given this analysis, plots that do not represent the isothermal expansion of an ideal gas are (B) and (D).

Therefore, the answer is: (B) and (D).