Which of the following conditions is favorable for $Van \ der \ Waals$ adsorption?

In an adsorption experiment,a graph between $\log (x/m)$ versus $\log P$ was found to be linear with a slope of $45^\circ$. The intercept on $\log (x/m)$ axis was found to be $0.3010$. The amount of gas adsorbed per gram of charcoal under a pressure of $0.5 \ atm$ is (in $g$)

In the Freundlich adsorption isotherm,the slope of the $AB$ line is:

If the adsorbate is held on a surface by weak Van der Waals forces,the adsorption process is called:

The substance used to decolourise and purify oils is

Which of the following adsorption isotherms represents the adsorption of a gas by a solid involving physical adsorption ($P_s =$ saturation pressure)?