Adsorption is multilayer in case of

Which of the following statements is $NOT$ true about absorption?

Why is adsorption always exothermic?

The following statements relate to the adsorption of gases on a solid surface. Identify the incorrect statement among them.

The validity of the Freundlich isotherm can be verified by plotting:

$10 \, mL$ of $1 \, mM$ surfactant solution forms a monolayer covering $0.24 \, cm^2$ on a polar substrate. If the polar head is approximated as a cube, what is its edge length?