1. Which of the following is water insoluble?
a) COO–
b) Na+
c) C17H35
d) All of the mentioned
Explanation: C17H35 is hydrophobic in nature and hence it is water insoluble.
2. The number of stearate ions required to form a micelle of colloidal size is ___________
a) 50
b) 60
c) 70
d) 80
Explanation: About 70 stearate ions aggregate to form a micelle of colloidal size.
3. Select the incorrect statement from the following options.
a) In the micelle formation, the water soluble heads are directed towards the centre
b) In the micelle formation, the water soluble heads are on the surface in contact with the water
c) In the micelle formation, the water insoluble tails are directed towards the centre
d) None of the mentioned
Explanation: In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water. All the other options are correct.
4. Select the correct statement from the following options.
a) The soap micelle is unstable due to positive charge on its head
b) The soap micelle is stable due to positive charge on its head
c) The soap micelle is unstable due to negative charge on its head
d) The soap micelle is stable due to negative charge on its head
Explanation: The soap micelle is stable due to the negative charge on its polar head. In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water.
5. The transition of ions to micelle is ___________
a) Reversible
b) Irreversible
c) All of the mentioned
d) None of the mentioned
Explanation: The transition of ions to micelle is a reversible process. In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water.
6. What is Critical Micelle Concentration?
a) The maximum amount of concentration that is required for the formation of micelle
b) The minimum amount of concentration that is required for the formation of micelle
c) The maximum amount of concentration that is not required for the formation of micelle
d) The minimum amount of concentration that is not required for the formation of micelle
Explanation: The minimum amount of concentration that is required for the formation of the micelle is termed as Critical Micelle Concentration (CMC). It is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system go to micelles.
7. Micelles behave as colloids only when?
a) Concentration is less than CMC
b) Concentration is equal to CMC
c) Concentration is greater than CMC
d) They always behave as colloids
Explanation: Micelles behave as colloids only when its concentration is greater than CMC. The CMC is an important characteristic of a surfactant. Before reaching the CMC, the surface tension changes strongly with the concentration of the surfactant. After reaching the CMC, the surface tension remains relatively constant or changes with a lower slope.
8. The conductivity of micelles is ___________
a) Higher than a colloidal solution
b) Lower than a colloidal solution
c) Equals to colloidal solution
d) None of the mentioned
Explanation: The conductivity of micelles is higher than the colloidal solution. And hence they can conduct more electric charges through them.
9. Which of the following is an example of top-down approach for the preparation of nanomaterials?
a) Gas phase agglomeration
b) Molecular self-assembly
c) Mechanical grinding
d) Molecular beam epitaxy
Explanation: Mechanical grinding is an example of top-down approach for the preparation of nanomaterials. All the other options are the example of bottom-up approach.
10. Which of the following is an example of bottom-up approach for the preparation of nanomaterials?
a) Etching
b) Dip pen nano-lithography
c) Lithography
d) Erosion
Explanation: Dip pen nanolithography is an example of bottom-down approach for the preparation of nanomaterials. All the other options are the example of top-down approach.