Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) on “Compressibility”.
1. What is the compressibility of ideal gases?
a) 1
b) 2
c) 3
d) 4
Answer: a
Clarification: Compressibility = PV/nRT, but for ideal gases PV = nRT, => Compressibility = 1.
2. Which of the following is true about compressibility of real gases?
a) Z = 1
b) Z < 1
c) Z > 1
d) Both Z < 1 and Z > 1
Answer: d
Clarification: For any value of compressibility except 1, the gas is real.
3. What is the pressure of CO2 gas with compressibility z = 0.8, if the ideal gas pressure of CO2 is 10 Pa, all other variables are same?
a) 5
b) 8
c) 10
d) 14
Answer: b
Clarification: Pressure of CO2 = 0.8*10 = 8 Pa.
4. What is the pressure of H2 with compressibility 0.6, molar volume 5 liter/mole at 27oC?
a) 2.9 atm
b) 5.4 atm
c) 9.6 atm
d) 14.5 atm
Answer: a
Clarification: P = znRT/V, => P = 0.6*0.0821*300/5 = 2.9 atm.
5. At what temperature, does SO2 with compressibility 2 has pressure 5 atm and molar volume 10 mole/s?
a) 300.5 K
b) 304.5 K
c) 310 K
d) 312.5 K
Answer: b
Clarification: T = PV/zR = 5*10/(2*0.0821) = 304.5 K.
6. What is the compressibility factor of water with density 1 g/liter at 27oC and 1 atm?
a) 0.25
b) 0.59
c) 0.73
d) 0.91
Answer: c
Clarification: z = PM/dRT = 1*18/(1*0.0821*300) = 0.73.
7. What is the compressibility factor of a liquid of molar mass 90 g and density 10 g/liter at 27oC and 2 atm?
a) 0.14
b) 0.39
c) 0.51
d) 0.73
Answer: d
Clarification: z = PM/dRT = 2*90/(10*0.0821*300) = 0.73.
8. What is the pressure of 80 grams of CH4 with compressibility 5, with 10 liter volume at 27oC?
a) 10.5 atm
b) 28.9 atm
c) 44.2 atm
d) 61.5 atm
Answer: d
Clarification: P = 5*5*0.0821*300/10 = 61.5 atm.
9. What is the compressibility of methane with density 10 g/liter at 27oC and 500 atm?
a) 32.5
b) 34.8
c) 39.6
d) 44.1
Answer: a
Clarification: z = PM/dRT = 500*16/(10*0.0821*300) = 32.5.
10. What is the compressibility of neon (molar mass = 20) with density 20 g/liter at 27oC and 100 atm?
a) 2.1
b) 3.5
c) 4
d) 6.8
Answer: c
Clarification: z = PM/dRT = 100*20/(20*0.0821*300) = 4.
11. 90 g glucose is filled in a container at 10 atm, if the volume of container is 2 liter, what is the temperature of glucose (z = 1.5)?
a) 25.4oC
b) 51.7oC
c) 76.9oC
d) 103.5oC
Answer: b
Clarification: T = PV/znR = 10*2/(1.5*0.5*0.0821) = 324.8 K = 51.7oC.
12. How many grams of C2H6 (z = 1.4) is present in the container at 27oC and 5 atm and with volume 10 liter?
a) 20 g
b) 30.4 g
c) 40.6 g
d) 50.8 g
Answer: c
Clarification: n = 5*10/(1.4*0.0821*300) = 1.45, mass of C2H6 = 1.45*28 = 40.6 g.
13. What is the volume of 21 g of propane (z = 1.9) at 1 atm and 27oC?
a) 23.4 liter
b) 37.5 liter
c) 42.1 liter
d) 59.6 liter
Answer: a
Clarification: V = 1.9*0.5*0.0821*300/1 = 23.4 liter.
14. 1 mole of cyclohexane (z = 1.2) is filled in a container at 27oC and 4 atm, what is the volume of container?
a) 3.8 liter
b) 4.4 liter
c) 5.6 liter
d) 7.4 liter
Answer: d
Clarification: V = 1.2*1*0.0821*300/4 = 7.4 liter.
15. 39 grams of benzene (z = 1.4) is filled in a container of volume 10 liter at 27oC, what is the pressure of container?
a) 1.7 atm
b) 1.9 atm
c) 2.2 atm
d) 2.5 atm
Answer: a
Clarification: P = 1.4*0.5*0.0821*300/10 = 1.7 atm.