Surface chemistry practice · Easy

Option C ($10-40$) is correct because the heats of adsorption in physisorption typically lie in the range of 10-40 kJ/mol.

Option B (Sorption) is correct because sorption is the process where both absorption and adsorption occur simultaneously.

Option D ($\mathrm{l}/n$ ($n$ being integer)) is correct because the slope of the Freundlich isotherm plot is 1/n, where n is an integer.

The correct answer is D (Both (1) and (3)) because both adsorption and occlusion describe the phenomenon of Pd absorbing 900 times its volume of hydrogen.

Option B is correct because $CO_2$ is a heterogenous gas and is adsorbed to a greater extent by activated charcoal compared to the other options.

Option D (An enzyme) is correct because enzymes are biological catalysts that speed up biochemical reactions.

Option D (gel) is correct because the addition of alcohol to a saturated aqueous solution of calcium acetate results in the formation of a gel, which is a liquid dispersed in a solid.

The correct answer is C (Solid, Liquid, Lyophobic) because in a gold sol, the dispersed phase is solid gold particles, the dispersion medium is a liquid (usually water), and it is a lyophobic colloid due to the weak interaction between gold and the liquid.

Option B (A liquid dispersed in a gas) is correct because a liquid aerosol is defined as a colloidal system where liquid particles are dispersed within a gaseous medium.

Option D (Sol) is correct because a sol is defined as a colloidal system with a solid dispersed phase and a liquid dispersion medium.

Option C is correct. A finely divided catalyst has a much larger surface area, providing more active sites for the reaction to occur.

Option C (Starch and cellulose) is correct because starch and cellulose are naturally occurring polymers with high molecular weights, fitting the definition of macromolecular colloids.

Option B (Colloidal silver) is correct because colloidal silver solutions are used in eye drops due to their antiseptic and antibacterial properties.

The correct answer is B (50 mL of 1 M AgNO_3 + 50 mL of 2 M KI) because an excess of I- ions will be adsorbed onto the AgI precipitate, forming a negatively charged colloid.

Option D (Both amount and sign of the charge) is correct because according to the Hardy-Schulze rule, the coagulating power of an ion is directly proportional to its charge and depends on the sign of the charge being opposite to that of the colloidal solution.

Option D (Inhibitor) is correct because acetamide slows down the decomposition of hydrogen peroxide, acting as a negative catalyst or inhibitor.

Option B (van der waals’ forces) is correct because in multimolecular colloidal solutions, atoms or molecules are held together by weak van der Waals' forces.

Option D (Kraft’s temperature) is correct because the Kraft temperature is the minimum temperature at which micelles form.

Option A (Alcohol to petrol) is correct because ZSM-5 is a zeolite catalyst used to convert alcohols directly into gasoline (petrol).

Option B (Lyophilic colloid) is correct because lyophilic colloids are solvent-loving, meaning they have a strong affinity for the dispersion medium.

Option A (Tyndall effect) is correct because the tails of comets are visible due to the scattering of light by dust particles, which is the Tyndall effect.

Option C (Coagulation) is correct because alum purifies muddy water through the process of coagulation, where it neutralizes the charge on the colloidal particles, causing them to clump together and settle down.

Option C (A gel) is correct because a gel is defined as a colloidal solution where the dispersed phase is a liquid and the dispersion medium is a solid.

Option C (To act as a catalyst promoter and increase activity of catalyst) is correct because molybdenum acts as a promoter in Haber's process, enhancing the iron catalyst's efficiency.

Option D (Cetyltrimethylammonium bromide) is correct because it is a cationic surfactant that forms cationic micelles in solution.

Option B (${\mathrm{V}_2}{\mathrm{O}_5}$) is correct because vanadium(V) oxide (${\mathrm{V}_2}{\mathrm{O}_5}$) is the catalyst used in the contact process for the manufacture of sulphuric acid.

Option D (Water vapours) is correct because activated charcoal has a high affinity for water vapor due to its polar nature and ability to form hydrogen bonds.

Option C (Vanadium pentoxide or Pt (asbestos)) is correct because these are the catalysts used in the contact process for sulfuric acid production.

Option D (Adsorption) is correct. Activated charcoal removes coloring matter through adsorption, where the colored substances adhere to the surface of the charcoal.

Option A (Dispersion of a solid or liquid in a gas) is correct because an aerosol is defined as a colloidal dispersion of solid particles or liquid droplets in a gas.