Following graph will be true when

Langmuir adsorption isotherm may be given as:

$\frac{\mathrm{x}}{\mathrm{m}}=\frac{\mathrm{ap}}{1+\mathrm{bp}}$

At high pressure . At high pressure bP >>> 1 So, 1+bP ≈ bP

$\therefore \frac{\mathrm{x}}{\mathrm{m}}=\frac{\mathrm{ap}}{\mathrm{bp}}=\frac{\mathrm{a}}{\mathrm{b}}$