This set of Food Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Dispersed Systems – Foams”.
1. Which is a substance formed by trapping pockets of gas in a liquid or solid?
a) Foam
b) Crystals
c) Gel
d) Emulsion
View Answer
Explanation: When gas is trapped in a liquid or solid foam is formed. In most foams, thin films of liquid or solid separates the large volume of gas. the regions of gas.
2. Solid foams can be closed-cell or open-cell.
a) True
b) False
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Explanation: The two types of solid foams are closed-cell foam and open-cell foam. Closed-cell foam is the gas formed in separate pockets surrounded by the solid material. In open-cell foam, gas pockets connect to each other.
3. A bath sponge is an example of closed-cell foam.
a) True
b) False
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Explanation: No, bath sponge is not an example of closed-cell foam opened-cell foam. Water easily flows through the bath sponge, discarding the air. An example of closed-cell foam is a camping mat.
4. At larger sizes foams are also called as __________
a) Honey comb
b) Bubble
c) Crystals
d) Gels
View Answer
Explanation: At larger size, foams are also called as honeycombs.
5. Stabilization of foam is caused by ___________
a) Dipole moment
b) Van der Waals forces
c) Covalent bond
d) Hydrogen bond
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Explanation: The van der Waals forces between the molecules in the foam, electrical double layers created by dipolar surfactants, and the Marangoni effect causes foam stabilization.
6. Which type of fire extinguisher is used for petroleum fire?
a) Powder type
b) Solid type
c) Foam type
d) Liquid type
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Explanation: Foam type extinguisher is used for oil type fire because it forms a layer on oil surface which prevents the oxygen to come in contact directly with oil called as smothering whereas powder is used for metallic fire and the process is called free radical quenching.
7. Which is the suitable evaporator for concentration of foaming liquids?
a) Long tube
b) Short tube
c) Vaccum
d) Falling film
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Explanation: The long-tube vertical evaporators are suitable for concentration of foaming liquids. Because they need less floor space and has high heat-transfer coefficients and can able to handle foamy liquids.
8. Which of the following extinguisher is suitable for cotton or other textile fire?
a) Dry chemicals
b) Soda acid
c) Water
d) Foam
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Explanation: Foam fire extinguishers are one of the most common types of fire extinguisher, and are generally used for fires involving flammable solids and liquids.
9. Which is the best suited to extinguishing oil or flammable liquid fire?
a) Dry chemicals
b) Soda acid
c) Water
d) Foam
View Answer
Explanation: Foam type extinguisher is best suited for oil type fire. Because it forms a layer on oil surface which blocks the oxygen’s exposure with the oil.
10. Firefighting foam was invented in which year?
a) 1947
b) 1902
c) 1925
d) 1987
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Explanation: Firefighting foam is a foam used for fire suppression. Fire-fighting foam was invented by the Russian engineer and chemist Aleksandr Loran in 1902.
11. Which type of foams is biodegradable?
a) Protein foams
b) Synthetic foams
c) Class A foams
d) Class B foams
View Answer
Explanation: Protein foams are biodegradable. Because they have natural proteins as the foaming agents. Synthetic foams, Class A and Class B foams are not biodegradable.
Sanfoundry Global Education & Learning Series – Food Chemistry.
To practice all areas of Food Chemistry, here is complete set of Multiple Choice Questions and Answers.
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