Q.1 Which of the following is an example of chemisorption?
Adsorption of nitrogen on activated charcoal
Adsorption of hydrogen on finely divided platinum
Adsorption of oxygen on ice
Adsorption of water vapor on silica gel
Explanation - Chemisorption involves chemical bond formation. Hydrogen adsorbing on platinum forms a chemical bond, unlike physical adsorption which involves weak van der Waals forces.
Correct answer is: Adsorption of hydrogen on finely divided platinum
Q.2 Which factor does NOT affect the rate of adsorption of a gas on a solid?
Pressure of the gas
Surface area of the solid
Temperature
Color of the solid
Explanation - Rate of adsorption depends on surface area, pressure, and temperature. Color has no influence.
Correct answer is: Color of the solid
Q.3 The Gibbs adsorption isotherm relates which quantities?
Surface tension and concentration
Viscosity and temperature
Boiling point and pressure
Solubility and molecular weight
Explanation - Gibbs adsorption isotherm describes how surface tension of a liquid changes with concentration of solute at the interface.
Correct answer is: Surface tension and concentration
Q.4 Which of the following is a lyophilic sol?
Colloidal gold in water
Starch in water
Sulphur in water
Arseno-sulphide in water
Explanation - Lyophilic sols have a strong affinity for the dispersion medium. Starch in water readily forms a stable colloid.
Correct answer is: Starch in water
Q.5 Which of the following is the main mechanism for the stabilization of lyophobic sols?
Viscosity enhancement
Electrostatic repulsion
Hydration
Hydrogen bonding
Explanation - Lyophobic sols are stabilized mainly by electrostatic repulsion due to adsorbed ions on particle surfaces.
Correct answer is: Electrostatic repulsion
Q.6 Which of the following increases adsorption of a gas on a solid?
Increasing temperature for physisorption
Increasing pressure
Decreasing surface area
Reducing gas polarity
Explanation - Adsorption generally increases with pressure because more gas molecules collide with the surface per unit time.
Correct answer is: Increasing pressure
Q.7 Which type of colloid can pass through a semipermeable membrane?
Lyophilic sol
Lyophobic sol
True solution
Coarse suspension
Explanation - True solutions (molecular solutions) can pass through a semipermeable membrane, unlike colloids.
Correct answer is: True solution
Q.8 Which of the following is an example of coagulation?
Formation of micelles in soap
Precipitation of alumina from aluminium hydroxide sol
Dissolving NaCl in water
Adsorption of nitrogen on charcoal
Explanation - Coagulation is the process where colloidal particles aggregate and settle out as precipitate, e.g., aluminium hydroxide sol coagulates to form precipitate.
Correct answer is: Precipitation of alumina from aluminium hydroxide sol
Q.9 Which of the following is a surface-active agent?
NaCl
Soaps
Glucose
Alcohols
Explanation - Surface-active agents (surfactants) reduce surface tension, e.g., soaps and detergents.
Correct answer is: Soaps
Q.10 Which phenomenon explains the spreading of a liquid on the surface of another liquid?
Adsorption
Catalysis
Surface tension reduction
Ostwald ripening
Explanation - Spreading occurs when surface tension is reduced at the interface, allowing the liquid to spread over another liquid.
Correct answer is: Surface tension reduction
Q.11 Which of the following is NOT a property of colloids?
Tyndall effect
Brownian motion
High osmotic pressure similar to true solutions
Complete filtration through ordinary filter paper
Explanation - Colloidal particles cannot pass through ordinary filter paper; only true solutions can.
Correct answer is: Complete filtration through ordinary filter paper
Q.12 In which type of adsorption does heat get evolved?
Chemisorption
Physisorption
Both A and B
Neither A nor B
Explanation - Adsorption is an exothermic process in both physical and chemical adsorption.
Correct answer is: Both A and B
Q.13 Which of the following is a lyophobic sol?
Starch in water
Colloidal sulphur in water
Gelatin in water
Protein in water
Explanation - Lyophobic sols have little affinity for the dispersion medium, e.g., colloidal sulphur in water.
Correct answer is: Colloidal sulphur in water
Q.14 Which effect is used to determine particle size in colloids?
Tyndall effect
Brownian motion
Coagulation
Catalysis
Explanation - Tyndall effect (scattering of light) helps estimate the size of colloidal particles.
Correct answer is: Tyndall effect
Q.15 Which of the following increases the rate of chemisorption?
Increasing temperature initially
Decreasing surface area
Decreasing pressure
Reducing the polarity of adsorbate
Explanation - Chemisorption generally requires activation energy; raising temperature initially increases the rate, but too high temperature may desorb the gas.
Correct answer is: Increasing temperature initially
Q.16 Which is used to remove permanent hardness from water?
Boiling
Colloidal alumina
Ion exchange resins
Filtration
Explanation - Permanent hardness caused by Ca²⁺ and Mg²⁺ salts cannot be removed by boiling but can be removed by ion exchange resins.
Correct answer is: Ion exchange resins
Q.17 Which of the following is an example of heterogenous catalysis?
Decomposition of H2O2 using KI
Haber process (N2 + 3H2 → 2NH3)
Enzyme-catalyzed reactions
Decomposition of sugar by acids
Explanation - Heterogenous catalysis involves catalyst in a different phase; Haber process uses solid Fe catalyst with gaseous reactants.
Correct answer is: Haber process (N2 + 3H2 → 2NH3)
Q.18 The phenomenon in which one substance spreads over the surface of another is called?
Adsorption
Surface wetting
Coagulation
Catalysis
Explanation - Surface wetting or spreading occurs when a liquid spreads over another surface due to intermolecular forces.
Correct answer is: Surface wetting
Q.19 Which of the following is used as a protective colloid in rubber latex?
Starch
Gelatin
Casein
Polyvinyl alcohol
Explanation - Protective colloids prevent coagulation of lyophobic sols, e.g., polyvinyl alcohol stabilizes rubber latex.
Correct answer is: Polyvinyl alcohol
Q.20 Which statement about physisorption is true?
It is specific
It decreases with increasing temperature
It involves chemical bond formation
It is irreversible
Explanation - Physisorption is due to weak van der Waals forces and is exothermic; raising temperature reduces adsorption.
Correct answer is: It decreases with increasing temperature
Q.21 Which of the following is an example of a multimolecular colloid?
Bentonite sol
Colloidal sulphur
Starch sol
Ferric hydroxide sol
Explanation - Multimolecular colloids are formed by aggregation of atoms or small molecules, e.g., colloidal sulphur.
Correct answer is: Colloidal sulphur
Q.22 Electrophoresis is used for which purpose?
Measuring surface tension
Determining particle charge and movement
Increasing adsorption
Stabilizing colloids
Explanation - Electrophoresis measures motion of charged colloidal particles under an electric field, providing information on their charge.
Correct answer is: Determining particle charge and movement
Q.23 Which of the following is true about micelles?
Formed only by hydrophilic molecules
Formed above critical micelle concentration (CMC)
Do not reduce surface tension
Always negatively charged
Explanation - Micelles are formed by amphiphilic molecules above a certain concentration called CMC; they reduce surface tension.
Correct answer is: Formed above critical micelle concentration (CMC)
Q.24 Which of the following is an example of adsorption from solution?
Catalytic decomposition of H2O2
Purification of sugar using animal charcoal
Formation of micelles by soap
Boiling hard water
Explanation - Animal charcoal adsorbs colored impurities from sugar solution, illustrating adsorption from solution.
Correct answer is: Purification of sugar using animal charcoal
Q.25 Which of the following is true for the rate of physisorption?
Increases with temperature
Decreases with temperature
Independent of pressure
Increases at very high temperature
Explanation - Physisorption is exothermic; increasing temperature decreases the extent of adsorption.
Correct answer is: Decreases with temperature