Which statements among the following are correct?

1. Freundlich isotherm fails at high pressure of the gas.

2. $$\Delta H < 0$$ for both physical and chemical adsorption.

3. Physical adsorption in non-selective.

4. Chemical adsorption is reversible, whereas physical adsorption is irreversible.

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 $$0.5 \mathrm{~atm}$$ is

Among the following, in which type of chromatography, both stationary and mobile phases are in liquid state?

The protective power of a lyophilic colloidal sol is expressed in terms of