This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Material Balance Concept”.
1. Which of the following does the concept of material balance based upon?
a) Conservation of mass
b) Conservation of energy
c) Conservation of momentum
d) Conservation of Volume
View answer
Explanation: Material is simply conservation of mass.
2. The equation of material balance, (Final condition + Sum of outputs) is equal to which of the following?
a) Initial condition – Sum of inputs
b) Initial condition + Sum of inputs
c) Sum of inputs – Initial condition
d) None of the mentioned
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Explanation: Equation of material balance is Final condition – Initial condition = Sum of inputs – Sum of outputs, => Final condition + Sum of outputs = Initial condition + Sum of inputs.
3. A container has 10 grams of water 5 grams of water is added and 2 grams of water is taken out, what is the final amount of water?
a) 7 grams
b) 10 grams
c) 13 grams
d) 15 grams
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Explanation: Final condition = Initial condition + sum of inputs – sum of outputs = 10 + 5 – 2 = 13 grams.
4. 10 moles of O2 is added to 10 moles of H2, how many moles of H2O will it produce?
a) 5
b) 10
c) 15
d) 20
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Explanation: Balanced equation is 2H2 + O2 -> 2H2O, => Moles of H2O = Moles of H2 = 10.
5. A combustion reaction has reactants 1 mole of CxHy and 2 moles of O2 and products 1 mole of CO2 and 2 mole of H2O, what is x + y?
a) 1
b) 3
c) 4
d) 5
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Explanation: Moles of C, H and O in reactants = Moles of C, H and O in products, => C: 1*x = 1*1 => x = 1, H: 1*y = 2*2 => x + y = 5.
6. In a random reaction 2 mole of CH4 and 1 mole of C2H4 are reacted, and 1 mole of C3H8 and 1 mole of CxHy are produced, what is x*y?
a) 2
b) 4
c) 8
d) 12
View answer
Explanation: Material balance for C: 2*1 + 1*2 =1*3 +1*x, => x = 1, for H: 2*4 + 1*4 = 1*8 + 1*y, => y = 4, => x*y = 4.
7. A reaction has reactants 2 moles of NaOH and 1 mole of H2SO4, and products Na2SO4 and H2O, what are the total moles of products?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Material Balance for Na: 2*1 = n1*2 => n1 = 1, for H: 2*1 + 1*2 = n2*2 => n2 = 2, => total moles of products = 1 + 2 = 3.
8. A reaction is A + 2B -> 3C, if 2 moles of A and 4 moles of B entered the system, what are the number of moles of C formed?
a) 2
b) 4
c) 6
d) 8
View answer
Explanation: Moles of C = 3*2 = 6.
9. 10 moles of A were present in a system initially, and 10 moles are added to it, it follows the reaction 4A -> B, what are the number of moles of B produced?
a) 5
b) 10
c) 15
d) 20
View answer
Explanation: Moles of B = (10 + 10)/4 = 5.
10. 10 moles of A were present in a system initially, and 10 moles of C are added to it, it follows the reaction 2A + C -> 5B, what is the number of moles of B produced?
a) 5
b) 10
c) 25
d) 50
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Explanation: Mole of B = 5*5 = 25.
11. There were 10 moles of a substance present initially in a system, 5 moles were added to it and a reaction occurred so that its moles are reduced by 20%, what are the final moles of a substance in the system?
a) 10
b) 12
c) 15
d) 18
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Explanation: Final moles of substance = (10 + 5)*80/100 = 12.
12. There were 15 moles of a substance present initially in a system, 25 moles were added to it and a reaction occurred so that its moles are reduced by 50%, what are the final moles of a substance in the system?
a) 10
b) 15
c) 20
d) 40
View answer
Explanation: Final moles of substance = (15 + 25)*50/100 = 20.
13. 10 moles of A were present in a system initially, and 12 moles of C are added to it, it undergoes the reaction 2A + 3C -> 2B, what are number of moles of B produced?
a) 4
b) 5
c) 8
d) 12
View answer
Explanation: Moles of B = 2*4 = 8.
14. 10 moles of A were present in a system initially, and 8 moles of C are added to it, it undergoes the reaction 5A + 3C -> 4B, what are number of moles of B produced?
a) 4
b) 6
c) 8
d) 10
View answer
Explanation: Moles of B = 4*2 = 8.
15. 8 moles of A were present in a system initially, and 24 moles of B are added to it, it undergoes the reaction 2A + 3B -> 4C + 5D, what are the number of moles of D produced?
a) 10
b) 20
c) 30
d) 40
View answer
Explanation: Moles of D = 5*4 = 20.
Sanfoundry Global Education & Learning Series – Basic Chemical Engineering.
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