Surface Chemistry

For a linear plot of log (x/m) versus log p in a Freundlich adsorption isotherm, which of the following statements is correct? (k and n are constants)

• 1/n appears as the intercept.

• Only 1/n appears as the slope.

• log (1/n) appears as the intercept.

• log (1/n) appears as the intercept.

The coagulating power of electrolytes having ions Na⁺, Al³⁺ and Ba²⁺ for arsenic sulphide sol increases in the order:

• Al³⁺<Ba²⁺<Na⁺

• Na⁺<Ba²⁺<Al³⁺

• Ba²⁺< Na²⁺<Al³⁺

• Ba²⁺< Na²⁺<Al³⁺

According to Freundlich adsorption isotherm, which of the following is correct?

The Tyndall effect is observed only when following conditions are satisfied:-
(a) The diameter of the dispersed particles is much smaller than the wavelength of the light used.
(b) The diameter of the dispersed particle is not much smaller than the wavelength of the light used.
(c) The refractive indices of the dispersed phase and dispersion medium are almost similar in magnitude.
(d) The refractive indices of the dispersed phase and dispersion medium differ greatly in magnitude.

• (a) and (d)

• (b) and (d)

• (a) and (c)

• (a) and (c)

Which of the following statements is incorrect regarding physissorptions?

• It occurs because of vander Waal’s forces.

• More easily liquefiable gases are adsorbed readily.

• Under high pressure, it results into multimolecular layer on the adsorbent surface.

• Under high pressure, it results into multimolecular layer on the adsorbent surface.

Gold numbers of protective colloids A, B, C and D are 0.50, 0.01, 0.10 and 0.005, respectively. The correct order of their protective powers is

•  D < A < C < B

• C < B < D < A

•  A < C < B < D

•  A < C < B < D

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.