The quenching of fluorescence depends on:

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.

Which of the following is not a surface phenomenon?

Which of the following statements are not true?

The correct statement$(s)$ about surface properties is(are):
$[A]$ Adsorption is accompanied by decrease in enthalpy and decrease in entropy of the system.
$[B]$ The critical temperatures of ethane and nitrogen are $563 \ K$ and $126 \ K$,respectively. The adsorption of ethane will be more than that of nitrogen on the same amount of activated charcoal at a given temperature.
$[C]$ Cloud is an emulsion type of colloid in which liquid is dispersed phase and gas is dispersion medium.
$[D]$ Brownian motion of colloidal particles does not depend on the size of the particles but depends on the viscosity of the solution.

Indicator type silica gel used as a dehumidifier contains