1. Which of the following is NOT a characteristic of physisorption?
a) It is exothermic
b) It occurs due to Van der Waals forces
c) It leads to the formation of multilayer adsorption
d) It involves the formation of chemical bonds
Answer:
d) It involves the formation of chemical bonds
Explanation:
Physisorption is a physical process and does not involve the formation of chemical bonds.
2. The Freundlich isotherm is represented by which of the following relations?
a) x/m = kP
b) x/m = kP^1/n
c) log(x/m) = log k + (1/n) log P
d) x/m = kP/n
Answer:
c) log(x/m) = log k + (1/n) log P
Explanation:
The Freundlich isotherm is given by the equation x/m = kP^1/n, which can be represented in a logarithmic form as mentioned in option c.
3. Which of the following is a positive colloid?
a) Fe(OH)3 sol
b) As2S3 sol
c) Soap solution
d) Starch solution
Answer:
a) Fe(OH)3 sol
Explanation:
Fe(OH)3 sol carries a positive charge and hence is a positive colloid.
4. The process of coagulation can be achieved by:
a) Heating
b) Mixing two oppositely charged sols
c) Persistent dialysis
d) All of the above
Answer:
d) All of the above
Explanation:
Coagulation can be brought about by various methods including heating, mixing of oppositely charged sols, and persistent dialysis.
5. Which of the following represents the correct order of increasing adsorption of gases on charcoal?
a) CO2 < O2 < NH3 < H2
b) H2 < O2 < CO2 < NH3
c) NH3 < H2 < CO2 < O2
d) O2 < H2 < CO2 < NH3
Answer:
b) H2 < O2 < CO2 < NH3
Explanation:
The ease of adsorption depends on the ease of liquefaction of the gas.
6. Which is NOT true for chemisorption?
a) It is specific in nature
b) It leads to the formation of a monolayer
c) It increases with the rise in temperature
d) It involves the formation of chemical bonds
Answer:
c) It increases with the rise in temperature
Explanation:
Chemisorption generally decreases with an increase in temperature beyond a certain point.
7. Which process is responsible for the purification of drinking water in household filters?
a) Dialysis
b) Absorption
c) Adsorption
d) Osmosis
Answer:
c) Adsorption
Explanation:
Activated charcoal in household filters adsorbs impurities, purifying the water.
8. The correct relationship between the extent of adsorption (x/m) and pressure P for adsorption of a gas on a solid is given by:
a) x/m is directly proportional to P
b) x/m is inversely proportional to P
c) x/m is proportional to the square root of P
d) x/m is proportional to P^2
Answer:
a) x/m is directly proportional to P
Explanation:
According to Freundlich's adsorption isotherm, x/m is directly proportional to P^1/n. For many cases, 1/n is 1, so x/m is directly proportional to P.
9. The Tyndall effect is observed in:
a) True solutions
b) Suspensions
c) Colloidal solutions
d) None of the above
Answer:
c) Colloidal solutions
Explanation:
The Tyndall effect is the scattering of light by colloidal particles, so it is observed in colloidal solutions.
10. Emulsions are a type of:
a) True solution
b) Colloidal solution
c) Suspension
d) None of the above
Answer:
b) Colloidal solution
Explanation:
Emulsions are colloidal dispersions where both the dispersed phase and the dispersion medium are liquids.
11. Which of the following is an example of a macromolecule?
a) Sulphur sol
b) Urea
c) Plastic
d) Rubber
Answer:
d) Rubber
Explanation:
Macromolecules are big molecules arising from the repetition of small simple units. Rubber is an example of such a molecule.
12. Which of the following colloids cannot be coagulated easily?
a) Lyophobic
b) Lyophilic
c) Both a and b
d) None of the above
Answer:
b) Lyophilic
Explanation:
Lyophilic sols are more stable and are not easily coagulated.
13. Which of the following methods is suitable for the separation of colloidal particles?
a) Chromatography
b) Crystallization
c) Sublimation
d) Distillation
Answer:
a) Chromatography
Explanation:
Chromatography is a technique used to separate mixtures and can be used to separate colloidal particles from a solution.
14. The charge on sol particles can be determined by:
a) Electrodialysis
b) Electroosmosis
c) Ultrafiltration
d) Ultracentrifugation
Answer:
b) Electroosmosis
Explanation:
Electroosmosis involves the movement of the dispersion medium under the influence of an electric field, helping determine the charge on sol particles.
15. What causes Brownian motion in colloids?
a) Gravity
b) Electric field
c) Unequal collisions by molecules of the dispersion medium
d) Magnetic field
Answer:
c) Unequal collisions by molecules of the dispersion medium
Explanation:
The random motion of colloidal particles, called Brownian motion, is caused by the unequal and random collisions by molecules of the dispersion medium.
16. A multimolecular colloid is one in which:
a) The dispersed phase has a macromolecular size
b) Aggregate of atoms or small molecules with a size less than 1 nm form species of range 1-1000 nm
c) Both the dispersed phase and dispersion medium are in the same phase
d) The dispersion medium is solid irrespective of the state of the dispersed phase
Answer:
b) Aggregate of atoms or small molecules with a size less than 1 nm form species of range 1-1000 nm
Explanation:
Multimolecular colloids involve aggregation of atoms or small molecules to achieve colloidal size.
17. The gold number of a protective colloid is:
a) The mass of gold required to just prevent the coagulation of 10 ml gold sol by 1 ml 10% NaCl solution
b) The mass of gold required to cause coagulation of 10 ml gold sol by 1 ml 10% NaCl solution
c) The number of milligrams of gold sol that can be protected by 1 gm of the protective colloid
d) The mass of the protective colloid required to just prevent the coagulation of 10 ml gold sol by 1 ml 10% NaCl solution
Answer:
d) The mass of the protective colloid required to just prevent the coagulation of 10 ml gold sol by 1 ml 10% NaCl solution
Explanation:
The gold number represents the protective power of a colloid. It is defined as the minimum amount of a protective colloid in milligrams which prevents the coagulation of 10 ml of a gold sol by 1 ml of 10% NaCl solution.
18. Hardy-Schulze rule relates to:
a) The coagulation of lyophilic sols
b) The greater the valence of the flocculating ion, the greater its power to cause precipitation
c) The coagulation of multimolecular colloids
d) The lesser the valence of the flocculating ion, the greater its power to cause precipitation
Answer:
b) The greater the valence of the flocculating ion, the greater its power to cause precipitation
Explanation:
According to the Hardy-Schulze rule, the greater the valence of the opposite ion present in the added electrolyte, the greater its power to cause precipitation.
19. Which of the following is NOT a method of preparation of colloids?
a) Condensation methods
b) Dispersion methods
c) Electrodialysis
d) Peptization
Answer:
c) Electrodialysis
Explanation:
Electrodialysis is a method for purification and not for preparation of colloids.
20. The phenomenon of adsorption finds applications in:
a) Creating high vacuums
b) Heterogeneous catalysis
c) Froth flotation process in metallurgy
d) All of the above
Answer:
d) All of the above
Explanation:
Adsorption is used in various processes, including creating high vacuums, in heterogeneous catalysis, and in the froth flotation process in metallurgy.