This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Units of Refrigeration – 1”.
1. At what K is the triple point of water?
a) 0 K
b) 4 K
c) 273.16 K
d) -273.16
View Answer
Explanation: At 273.16 K, i.e. 0C water contains all the three forms, solid, liquid as well as gas partially.
2. What is the relation between Celsius and Fahrenheit scale?
a) \(\frac{C}{9} = \frac{F-32}{5}\)
b) \(\frac{C}{5} = \frac{F-32}{9}\)
c) \(\frac{C}{32} = \frac{F-32}{5}\)
d) \(\frac{C}{5} = \frac{F-9}{32}\)
View Answer
Explanation: It is derived by using the following relation, \(\frac{C}{100} = \frac{F-32}{180}\) because, in the scale developed by Fahrenheit in 1742, the freezing point of water was at 32 and boiling was at 212, i.e. 180 points difference, Whereas for Celsius scale the difference is 100 units (0C to 100C).
3. What does 298 Kelvin mean on Celsius scale?
a) 27 C
b) 25 C
c) 15 C
d) 35 C
View Answer
Explanation: As for conversion of Kelvin to Celsius 273 is to be deducted, hence 298 K = 298 – 273 = 25C.
4. What is the value of 110 C on the Fahrenheit scale?
a) 198 F
b) 383 F
c) – 73 F
d) 230 F
View Answer
Explanation: According to the relation, \(\frac{C}{5} = \frac{F-32}{9}\)
\(\frac{110}{5} = \frac{F-32}{9}\)
F-32 = 198
F = 230 F.
5. 1 Pascal = 1 _____
a) N/mm2
b) N/m3
c) N/m2
d) N/mm3
View Answer
Explanation: Pascal is the unit generally used to express pressure, which means the amount of pressure in Newton, divided by the area i.e. square meters.
6. 1 Bar = ______
a) 1×105 N/m2
b) 1×109 N/m2
c) 1×105 N/mm2
d) 1×106 N/m2
View Answer
Explanation: Bar is the unit used for expressing the higher level of pressure, which means 760 mm of Hg at the sea level, which equals to 100,000 Newton.
7. 1 Bar = ______ mm of Hg.
a) 100
b) 720
c) 760
d) 360
View Answer
Explanation: Sometimes pressure is represented in the form of height of mercury in the tube of 1 mm2 area, i.e. 760 mm practically for 1 bar pressure.
8. What is absolute zero temperature?
a) 0 C
b) 273 C
c) -273 K
d) -273 C
View Answer
Explanation: Temperature of -273 C i.e. 0 K is called absolute zero temperature, as it’s not possible to go beyond that temperature on the earth.
9. What are the temperature and pressure for S.T.P. (Standard Temperature Pressure)?
a) 0 C, 1 bar
b) 273 C, 15 bar
c) 288 K, 1 bar
d) 273 K, 1 bar
View Answer
Explanation: Generally, 15 C is taken as the standard temperature, i.e. 288 K and pressure is 760 mm of Hg or 1 bar.
10. What are the temperature and pressure for N.T.P. (Normal Temperature Pressure)?
a) 0 C, 1 bar
b) 273 C, 15 bar
c) 288 K, 1 bar
d) 273 K, 1 bar
View Answer
Explanation: Generally, 0 C is taken as the standard temperature, i.e. -273 K and pressure is 760 mm of hg or 1 bar.
Sanfoundry Global Education & Learning Series – Refrigeration & Air Conditioning.
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