250+ TOP MCQs on Analyses of Multicomponent Solutions and Mixtures and Answers

Chemical Engineering Interview Questions and Answers on “Analyses of Multicomponent Solutions and Mixtures”

1. What is the molecular weight of a mixture that contains 25% CO₂, 40% O₂ and 35% N₂?
a) 11.2 g
b) 22.4 g
c) 33.6 g
d) 44.8 g
Answer: c
Clarification: Molecular weight = (25*44 + 40*32 + 35*28)/100 = 33.6 g.

2. What is the weight of 10 moles of a mixture with composition 15% O₂, 25% SO₂, 30% COCl₂, 25% SO₃ and 5% N₂?
a) 124
b) 345
c) 507
d) 719
Answer: d
Clarification: Molecular weight of mixture = (15*32 + 25*64 + 30*99 + 25*80 + 5*28)/100 = 71.9, => Weight of mixture = 71.9*10 = 719.

3. If a compound contains 48% of Carbon, 48% of oxygen and 8% of hydrogen by weight, then what is the possible molecular formula of the compound?
a) C₂H₄O
b) CH₄O₃
c) C₄H₄O₃
d) C₄H₈O₃
Answer: d
Clarification: Ratio of number of atoms, Carbon: Hydrogen: Oxygen = 48/12: 8/1: 48/16 = 4:8:3.

4. A compound contain 12% of carbon, 16% of oxygen, 28% of nitrogen, 4% of hydrogen and 40% calcium by weight, then what can be the possible formula of the compound?
a) C₂H₃N₂Ca(OH)
b) CH₄N₄Ca₂(OH)
c) CH₃N₂Ca₂(OH)
d) None of the mentioned
Answer: c
Clarification: Ration of number of atoms, carbon: hydrogen: oxygen: nitrogen: calcium = 12/12: 4/1: 16/16: 28/14: 40/20 = 1:4:1:2:2.

5. What is the value of x in C₂H₈(OH)x if the percentage by weight of hydrogen is 12%?
a) 1
b) 2
c) 3
d) 4
Answer: d
Clarification: Let the total weight of the compound be 100 g, => weight of hydrogen in the compound is 12 g, => x = 12 – 8 = 4.

6. If hydrogen is 14% by weight in CH₃(OH)_x(NH₃)_y, then what is the possible value of x*y?
a) 6
b) 12
c) 18
d) 24
Answer: a
Clarification: Let the weight of compound be 100 g, => weight of hydrogen = 14 g, => 3y + x + 3 = 14 => 3y + x = 11, => and 12 + 14 + 16x + 14y = 100, => 8x + 7y = 37, solving both equations we get x = 2 and y = 3, => x*y = 6.

7. A liquid mixture of O₂, CH₄ and CO has the composition 32% O₂, 16% CH₄ and 52% CO, then what is the mole fraction of CH₄?
a) 0.1
b) 0.2
c) 0.25
d) 0.5
Answer: b
Clarification: Let the total weight of the mixture be 100 g, => weight of each component are 32 g, 16 g and 52 g respectively, => moles of O₂ = 32/16 = 2, moles of CH₄ = 16/16 = 1, moles of CO = 52/26 = 2 g, => mole fraction of CH₄ = 1/5 = 0.2.

8. A gaseous mixture is composed of 20% CO₂, 40% O₂ and 40% N₂. What is the mass fraction of N₂?
a) 0.307
b) 0.416
c) 0.529
d) 0.784
Answer: a
Clarification: Let the total moles of the mixture be 100, => mass of CO₂ = 20*44 = 880 g, mass of ¬O₂ = 40*16 = 640 g, mass of N₂ = 40*14 = 560 g, => mass fraction of N₂ = 560/(880 + 640 + 560) = 0.307.

9. A liquid mixture composed of 20% CH₄, 30% C₂H₄, 35% C₂H₂, and 15% C₂H₂O. What is the average molecular weight of the mixture?
a) 20
b) 25
c) 6.75
d) 9.25
Answer: b
Clarification: Since it is a liquid mixture so the percentages are by weight, => average molecular weight of mixture = (20 + 30 + 35 + 15)/4 =25.

10. A gaseous mixture composed of 20% CH₄, 30% C₂H₄, 35% C₂H₂, and 15% C₂H₂O. What is the average molecular weight of the mixture?
a) 20
b) 25
c) 6.75
d) 9.25
Answer: c
Clarification: Since it is a gaseous mixture so the percentages are by mole, => average molecular weight of mixture = {(20/100)*16 + (30/100)*28 + (35/100)*26 + (15/100)*42}/4 = 6.75.

11. The mole percent of H₂ and N₂ in a mixture is 50% each, what is the mass percentage of H₂?
a) 12.5
b) 25
c) 50
d) 87.5
Answer: a
Clarification: Let the moles be 50 each, => Mass of H₂ = 100, Mass of N₂ = 700, => Mass percentage of H₂ = 100/(100 + 700)*100 = 12.5%.

12. The mole percent of CO₂ and H₂O in a mixture is 40% and 60% respectively, what is the mass percent of CO₂?
a) 24.1
b) 47.2
c) 61.9
d) 78.5
Answer: c
Clarification: Let the moles be 40 and 60, => mass of CO₂ = 40*44 = 1760, mass of H₂O = 1080, => mass percent of CO₂ = 61.9%.

13. A mixture contains 20% CO₂, 30% SO₂ and 50% H₂O, what is the mass percent of CO₂?
a) 23
b) 45
c) 66
d) 87
Answer: a
Clarification: Let the moles be 20, 30 and 50, => mass percent of CO₂ = (20*44)/[20*44 + 30*64 + 50*18] = 23%.

14. A mixture contains 20% NaCl, 30% CH₄ and 50% H₂O, what is the mass percent of NaCl?
a) 21
b) 34
c) 45
d) 68
Answer: b
Clarification: Mass percent of NaCl = 20*35.5/[20*35.5 + 30*16 + 50*18] = 34%.

15. A mixture contains 10% CO, 40% CO₂ and 50% H₂O, what is the mass percent of CO₂?
a) 9.5
b) 15.4
c) 39.5
d) 74.1