Colloids and GPAT

 

1. An example for colloidal systems is:

A. clays and gels

B. ointments and pastes

C. solutions of soaps and proteins

D. suspensions

C.solutions of soaps and prote

2. The criterion to call a system ‘colloid’ is

A. a fine state of subdivision of dispersed phase

B. dispersed particles are in the size range of 1 nm to 1 µm

C. interface is very extensive

D. the presence of dispersed phase in a dispersion medium

B.dispersed particles are in the size range of 1 nm to 1 µm

3. Solutions of proteins and starch in water are the examples of the colloidal type:

A. hydrophilic

B. hydrophobic

C. lyophilic

D. lyophobic

A.hydrophilic

4. Electrodialysis method is employed in the colloidal chemistry for the purpose of :

A. Indentification

B. preparation

C. Purification

D. Stabilization

C.Purification

5. Silica gel is an example for the type of gel:

A. dilatants

B. elastic

C. rigid

D. thixotropic

C.rigid

6. Which of the following DO NOT form colloid spontaneously?

A. association

B. lyophilic

C. lyophobic

D. micellar

C.lyophobic

7. Sulphur sol is an example of colloidal type:

A. Association

B. hydrophilic

C. lyophilic

D. lyophobic

D.lyophobic

8. Thixotropic type of behavior is shown by the gel:

A. bentonite

B. pectin

C. silica

D. starch

A.bentonite

9. In the determination of size, shape and structure of colloidal particles, which one of the following CANNOT be used?

A. electron microscope

B. instrument measuring light scattering

C. Langmuir film balance

D. ultramicroscope

D.ultramicroscope

10. Surfactant solutions are termed as association colloids when their concentrations are:

A. insufficient to saturate the bulk phase

B. insufficient to saturate the interface

C. less than critical micellar concentration (cmc)

D. more than cmc

D.more than cmc

11. Name the type of colloidal dispersion to which electrolytes are normally added in small quantities to stabilize:

A. association

B. lyophilic

C. lyophobic

D. micellar

C.lyophobic

12. Protective colloids DO NOT:

A. aid in dispersion

B. decrease the zeta potential

C. lower the interfacial tension

D. offer a mechanical barrier

C.lower the interfaci

Q) Which is water loving.

A. association

B. hydrophilic

C. hydrophobic

D. lyophilic

C.hydrophobic

14. In high concentrations, electrolytes destabilize a lyophilic sol by a process termed as :

A. coagulation

B. dilution

C. salting out

D. solvation

C.salti

15. Which quality of the dispersed phase is responsible for the increased viscosity of a hydrophiliccolloidal dispersion?

A. charge

B. shape

C. size

D. surface area

D.surface area

16. Dispersion of acacia in water gives the colloid of type:

A. association

B. negative

C. neutral

D. positive

B.negative

17. Addition of alcohol to a hydrophilic colloid leads to:

A. crystallization

B. hydration

C. precipitation

D. stabilization

C.precipitation

18. The critical value of zeta potential (in milli volts) for a stable colloid (except gold sol) is:

A. from 20 to 50

B. from 50 to 100

C. less than 20

D. mor than 100

A.from 20 to 50

19. If kinetic energy of interaction is about 25 kT (Where k is gas constant), the system can be consideredto have:

A. deflocculated state

B. long half life

C. short half life

D. weak attractiton forces

B.long half life

20. In foams, the dispersed phase and dispersion medium, respectively, are:

A. gas and liquid

B. gas and solid

C. liquid and gas

D. solid and gas

A.gas and liquid

21. The characteristic of a lyophobic sol is that:

A. electrolytes in small amounts induce stabilization

B. it is reversible

C. particles have high electric charge

D. viscosity increases by the presence of particles

C.particles have high electric charge

22. Hydrosol refers to a system in which the dispersed phase and dispersion medium, respectively, are:

A. gas and water

B. liquid and water

C. solid and water

D. water and solid

C.solid and water

23. Electrodialysis is used, when impurities in a sol are:

A. amphiphiles

B. colloids

C. electrolytes

D. nonelctrolytes

C.electrolytes

24. Under ultramicroscope, colloid particles appear as:

A. bright specks against dark background

B. concentric rings

C. dark specks against bright background

D. fluorescent specks

A.bright specks against dark background

25. Which one of the following properties is extensively applied for determining the molecular weight ofpolymer?

A. depression of freezing point

B. elevation of boiling point

C. lowering of vapour pressure

D. osmotic pressure

D.osmotic pressure