This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Colloids – 1”.
1. What is the size of colloidal particles?
a) 10-20 nm
b) More than 20 nm
c) Less than 10 nm
d) 30 to 50 nm
View Answer
Explanation: Since colloidal are intermediate between powdered particles and suspension particles, they have a size in between these particles of about 10 to 20 nm. These are considered to be intermediate size of molecules.
2. Which of the following is a characteristic of a colloid?
a) It forms 2 layers with a solution
b) It forms turbid layers
c) It forms heterogeneous layer
d) It forms a homogeneous layer
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Explanation: Since a colloidal particle does not from a single layer with solvents, the only possibility is to form a turbid layer where the solution is an intermediate between a miscible and immiscible solution.
3. Where does colloidal solution find application in?
a) In milk industries
b) In chromatic chemical industries
c) In crystallography
d) In textiles
View Answer
Explanation: Since colloidal solutions can easily be emulsified with the help of emulsifying agents such as ethylene dichloride, it can find its major application in the field of dairy industries.
4. Calculate the size of the colloidal particle present in the mixture of fats and milk from the given data.
Amount of milk in litres: 20
Amount of fats in grams: 10
Time taken to mix the ingredients: 20 sec
a) 3
b) 6
c) 4
d) 61
View Answer
Explanation: The size of the colloidal particles can be given by the formula
Size=amount of solvent x time/ amount of colloidal. Therefore in this problem, we can see that the size of the colloid is 20 x 20 / 10 = 4.
5. During an experiment, accidently iodine got mixed up with a biological sample of proteins and polys. Identify the smallest colloid that can be obtained during the process of separation.
a) Fats
b) Amino acids
c) Polys
d) R molecules
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Explanation: Given that the solution of iodine got mixed up with milk sample, we know milk is already a colloidal solution of polymers like amino acids, proteins, fats, vitamins etc, the smallest among all these colloidal particles is amino acids.
6. Which of the following form of colloid is considered to be the strongest colloid?
a) Gel
b) Foam
c) Solid sol
d) Liquid sol
View Answer
Explanation: We know that solid sol is the colloidal solution of a solid and a solid. Since there is a mixture of solid and solid, the bond between them is quite strong. Thus it is considered to be the strongest colloid.
7. Which of the following form of colloid is considered to be the lightest colloid?
a) Gaseous foam
b) Solid sol
c) Sol
d) Liquid sol
View Answer
Explanation: We know that the gaseous foam is the colloidal solution of gaseous molecules and liquid. Thus there exists a lighter bond between the particles. Thus this is considered as the lightest colloid.
8. What is the size of normal an amino acid?
a) 1 to 2 nm
b) 2 to 3 nm
c) 4 to 5 nm
d) 2 to 5 nm
View Answer
Explanation: We know that amino acids are nothing but single structure monomers of proteins. Thus they are visible only under an ultra microscope due to is an extreme small size in the range of nano meters. Their size ranges from 1 to 2 nm.
9. What is called a dispersion phase?
a) It is the main layer
b) It is the secondary layer in which the colloidal particles are dispersed
c) It is the secondary layer
d) It is the basic colloidal layer
View Answer
Explanation: Since the colloidal particles require a layer in which it has to be dispersed, the dispersion phase is considered to be a second layer. The dispersion phase is generally a solvent.
10. What is called a dispersion medium?
a) It is where the dispersed phase settles
b) It is where the solute particles settle
c) It is where the dispersed phase is suspended
d) It is the primary medium
View Answer
Explanation: Since to form a stable colloidal solution, the dispersed phase requires a stable solvent medium is required. This is the condition in which equilibrium is achieved. This medium is called a dispersion medium.
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