This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Refrigerants – Chemical Properties”.
1. What is right about the flammability of halo-carbon refrigerants?
a) They possess low flammable properties
b) They possess incredibly high flammable properties
c) They are not flammable
d) They possess little flammable properties
Explanation: Halo-carbon contains Hydrogen, Carbon, Chlorine, and Fluorine. Though hydrogen itself is highly flammable and when combined with carbon also given flammable compounds. But when Hydrogen, Carbon, Chlorine, and Fluorine are combined, gives very stable compounds.
2. What is right about the explosive properties of halo-carbon refrigerants?
a) They are not flammable
b) They possess incredibly high explosive properties
c) They possess low explosive properties
d) They possess low explosive properties
Explanation: Halo-carbon contains Hydrogen, Carbon, Chlorine, and Fluorine. Though hydrogen itself is highly explosive and when combined with carbon also given explosive compounds. But when Hydrogen, Carbon, Chlorine, and Fluorine are combined, gives very stable compounds, which are not explosives.
3. In what proportion when Ammonia mixed with air becomes explosive?
a) 10 – 15 % gas by volume
b) 16 – 25 % gas by volume
c) 10 – 15 % gas by weight
d) 16 – 25 % gas by weight
Explanation: Ammonia is somewhat flammable but becomes explosive when mixed with air in the ratio 16 to 25 % gas by volume. Explosive property of ammonia is also widely used in applications.
4. By what ratio, R – 22 has more solubility in water than R – 12?
Explanation: The solubility of water with R – 22 is more than R – 12 by the ratio 3:1. If more water is present than solubility, ice forms and operation hindrance occurs.
5. A wetted cloth is put at the point of the leak in ammonia refrigeration plants.
Explanation: To avoid harms to the person working in ammonia refrigeration plants, a wetted cloth is put at the point of leak due to the property of ammonia being highly soluble in water.
6. What is the ability of refrigerant to mix with oil called?
d) Solubility of water
Explanation: Ability of refrigerant to mix with oil is called as miscibility. Miscibility is a secondary factor in the selection of refrigerant. The solubility of water is the ability to mix with water. Whereas, flammability and toxicity have no relevance with the mixing of refrigerants.
7. Among the following refrigerants, which is having relatively higher miscibility?
b) R – 12
c) Carbon dioxide
d) Sulphur dioxide
Explanation: R – 12 is relatively more miscible than other refrigerants. It is miscible under all operating conditions due to a more stable structure of the compound. Not only R – 12 but also all refrigerants of Freon group possess higher miscible properties than NH3, CO2, and SO2.
8. What is right about Ammonia?
a) Ammonia is insoluble in water
b) Ammonia spoils the taste of fruits and vegetables when mixed with water
c) Ammonia does not affect the taste of fruits and vegetables when mixed with water
d) Ammonia is not toxic
Explanation: Ammonia is highly soluble in water. After dissolving easy in water, it becomes alkaline or basic. As most of the fruits and vegetables are acidic. Ammonia reacts with these products, and salt formation occurs, and the taste of these products is spoiled totally.
9. Among the following refrigerants, which is the odd refrigerant as per the criterion of toxicity?
a) R – 11
b) R – 12
c) R – 22
d) R – 30
Explanation: R – 30 is the odd man out among the given refrigerants. It produces a serious effect when given time of just 30 minutes of exposure. Toxicity is very high as compared to given refrigerants.
R – 11, R – 12, and R – 22 need 120 minutes of exposure to produce the serious effect of toxicity.
10. R – 764, i.e., Sulphur dioxide is the least toxic refrigerant.
Explanation: Sulphur dioxide is the most toxic refrigerant among all refrigerants. It needs just 5 minutes of exposure to produce a serious effect and which are hazardous. Only 0.7% by volume in the air is the requirement to produce this toxicity effect.
Sanfoundry Global Education & Learning Series – Refrigeration & Air Conditioning.
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