Question

The following graph represents the T-V curves of an ideal gas ( where T is the temperature and V the volume) at three pressures P1, P2 and P3 compared with those of Charles's law represented as dotted lines.

Then the correct relation is :

• A. P3 > P2 > P1
• B. P1 > P3 > P2
• C. P2 > P1 > P3
• D. P1 > P2 > P3

Answer 1

Answer: (D)

P1 > P2 > P3

Answer 2

According to the ideal gas law:

$PV = nRT \implies V = \frac{nRT}{P}$.

For a fixed number of moles, $V \propto \frac{T}{P}$. At a given temperature, as pressure increases, the slope of the $T-V$ curve (from the origin) decreases.
Thus:

$P_1 > P_2 > P_3$ (higher pressure corresponds to a steeper curve).