Colloidal dispersion or colloid is a heterogeneous system, which is neither a suspension nor a solution. Here very fine particles known as dispersed phase are present throughout the dispersion medium. The particle size of the dispersed phase in the colloid is bigger than that of a solution but smaller than suspensions. The colloids are classified based on the type and physical state of particles and also dispersion medium. Some examples of colloids are gel, sol, foam, emulsion, aerosol, etc.
1. Fog is an example of which type of colloidal system?
(a) Gas in liquid
(b) Solid in gasLiquid in gas
(c) Gas in gas
(d) Liquid in gas
Answer: (b)
2. Which of the following properties of colloids does not depend on the charge on particles?
(a) Coagulation
(b) Electro-osmosis
(c) Electrophoresis
(d) Tyndall effect
Answer: (d)
3. The term used to determine the protecting power of a lyophilic colloid is
(a) oxidation number
(b) coagulation value
(c) gold number
(d) critical micelle concentration
Answer: (c)
4. This method is commonly used for destruction of colloid
(a) Addition of electrolytes
(b) Condensation
(c) Dialysis
(d) Filtration by animal membrane
Answer: (a)
5. Which of the following compounds form micelles, if their concentration is increased in aqueous solution?
(a) Urea
(b) Glucose
(c) Pyridinium chloride
(d) Dodecyl trimethyl ammonium chloride
Answer: (d)
6. If the concentration of surfactant molecules increases above the critical micelle concentration (CMC), then they
(a) become soluble
(b) dissociate
(c) associate
(d) decompose
Answer: (c)
7. The ability of an ion to coagulate a given colloid is dependent on the
(a) only charge
(b) magnitude
(c) both magnitude and charge
(d) sign of the charge
Answer: (c)
8. The diameter of particles in colloidal system is
(a) 10-9 m to 10-6 m
(b) 10-10 m to 10-4 m
(c) 10-12 m to 10-9 m
(d) 10-7 m to 10-5 m
Answer: (a)
9. Which of the following is an associated colloid?
(a) Soap
(b) Sol of gold
(c) Proteins
(d) Starch
Answer: (a)
10. The position occupied by non-polar hydrophobic and polar hydrophilic group in a micelle is
(a) non-polar towards the outside and polar towards inside
(b) polar towards the outside and non-polar towards inside
(c) both present only at the surface
(d) both distributed throughout
Answer: (b)
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