According to Langmuir adsorption isotherm, the amount of gas absorbed by unit surface area is : (a,b,,k and n are constants; P=pressure of gas)

Question

$$\begin {array} {1 1} (a)\;k.P^n & \quad (b)\;\frac{1+bP}{aP} \\ (c)\;k.P^{1/n} & \quad (d)\;\frac{a P}{1+bP} \end {array}$$