261.

The disperse phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged, respectively, which of the following statements is NOT correct?

• magnesium chloride solution coagulates, the gold sol more readily than the iron (III) hydroxide sol.

• sodium sulphate solution causes coagulation in both sols

• mixing the sols has no effect

• mixing the sols has no effect

Point out the false statement.

• Colloidal sols are homogeneous

• Colloids carry + ve or - ve charges

• Colloids show Tyndall effect

• The size range of colloidal particles is 10-1000 $\stackrel{°}{\mathrm{A}}$

The amount of electrolytes required to coagulate a given amount of Agl colloidal solution (-ve charge) will be in the order

• NaNO₃> Al₂(NO₃)₃ > Ba(NO₃)₂

• Al₂(NO₃)₃ > Ba(NO₃)₂ >NaNO₃

• Al₂(NO₃)₃ > NaNO₃ > Ba(NO₃)₂

•  NaNO₃ > Ba(NO₃)₂ >Al₂(NO₃)₃

Which one of the following is a case of negative adsorption?

• Acetic acid solution in contact with animal charcoal.

• Dilute KCl solution in contact with blood charcoal.

• Concentration KCl solution in contact with blood charcoal

• H₂ gas in contact with charcoal at 300 K.

Peptisation involves

• precipitation of colloidal particles

• disintegration of colloidal aggregates

• evaporation of dispersion medium

• impact of molecules of the dispersion medium on the colloidal particles

In Langmuir's model of adsorption of a gas on a solid surface,

• the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered

• the adsorption at a single site on the surface may involve multiple molecules at the same time

• the mass of gas striking a given area of surface is proportional to the pressure of the gas

• the mass of gas striking a given area of surface is independent of the pressure of the gas

Which one of the following is most effective in causing the coagulation of an As₂S₃ sol?

• KCl

• AlCl₃

• MgSO₄

• K₃Fe(CN)₆

The continuous phase contains the dispersed phase throughout, example is

• water in milk

• fat in milk

• water droplets in mist

• oil in water

Peptization denotes

• digestion of food

• hydrolysis of proteins

• breaking and dispersion into colloidal state

• precipitation of solid from colloidal dispersion

Blue colour of water in sea is due to

• refraction of blue light by impurities

• refraction blue sky by water

• scattering of light by water

• None of the above