Adding soap to water ................

Which of the following is not a surface phenomenon?

Identify the correct statement$(s)$ from the following:
$a$) Protective power of a lyophilic sol is more if its gold number is more
$b$) In the coagulation of negative sols,the coagulating power of cations follow the order $Na^{+} > Ba^{2+} > Al^{3+}$
$c$) Cloud is a solid in gas type of colloid
$d$) Physical adsorption is non-specific and multilayered at high pressure.

$0.27 \ g$ of a long chain fatty acid was dissolved in $100 \ cm^3$ of hexane. $10 \ mL$ of this solution was added dropwise to the surface of water in a round watch glass. Hexane evaporates and a monolayer is formed. The distance from edge to centre of the watch glass is $10 \ cm$. What is the height of the monolayer? [Density of fatty acid $= 0.9 \ g \ cm^{-3}, \pi = 3$]

Setting of cement is an

Which of the following statements is/are not correct?
$(A)$ Adsorption is accompanied by decrease in enthalpy as well as decrease in entropy of the system.
$(B)$ Gases, which can react strongly with adsorbent show chemisorption.
$(C)$ When the value of the slope of the Freundlich isotherm is non-zero, adsorption is independent of pressure.
$(D)$ Gold number of potato starch is $0.15$.