The lubricating action of an oil is more if it possesses:

Sodium thiosulphate is used in photography to :-

Identify the correct statements from the following.
$(i)$ In the oxidation of oxalic acid with $KMnO_4$ in acid medium, $Mn^{2+}$ acts as an autocatalyst.
$(ii)$ $CdS$ colloidal solution can be precipitated by the addition of $Cl^{-}$ ions.
$(iii)$ The gold numbers of three protective colloids $(A, B, C)$ are $0.03$, $25$, and $0.25$ respectively. Their protective power follows the order $A > C > B$.
$(iv)$ Physisorption is an irreversible process.

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 $0.15$.

The quenching of fluorescence depends on: