# Chemical Process Calculation Questions and Answers – Material balances for a Combustion System-I

This set of Chemical Process Calculation Multiple Choice Questions & Answers (MCQs) focuses on “Material balances for a Combustion System-I”.

1. 144 grams of C5H12 is burnt with 2 molesO2, and 1 mole of CO2 is produced.
What is the percentage of excess O2?
a) 25%
b) 50%
c) 75%
d) 100%

Explanation: Percentage of excess oxygen = 100*(2 – 1.6)/1.6 = 25%.

2. For a combustion system, incorrect statement is
a) Reaction of oxygen with materials containing hydrogen, carbon and sulfur
b) Product gases are such as C3H8O, CO2, CO, SO2
c) Most combustion processes use air as the source of oxygen.
d) None of the mentioned

Explanation: Properties of a combustion system.

3. All the gases resulting from a combustion process including the water vapour is known as
a) Flue gas
b) Dry basis
c) Orsat analysis
d) None of the mentioned

Explanation: All the gases resulting from a combustion process including the water vapour is known as flue gas.

4. Ethane is burnt with 150% of excess air then what is the percentage of O2 in the products?
a) 12.5%
b) 33.3%
c) 45.4%
d) 52.9%

Explanation: Percentage of O2 = 45/85*100 = 52.9%.

5. All the gases resulting from a combustion process, not including the water vapour is known as
a) Flue gas
b) Stack gas
c) Orsat analysis
d) None of the mentioned

Explanation: All the gases resulting from a combustion process, not including the water vapour is known as Orsat analysis.
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6. A complete combustion reaction is
a) Fuel producing CO2
b) Fuel producing CO and C3H8O
c) Fuel producing CO2 and C3H8O
d) Fuel producing CO and C3H8

Explanation: A complete combustion reaction is where Fuel is producing CO2 and C3H8O.

7. Two statements are given as below
A. A fuel is producing some CO from the carbon source is the partial combustion of that fuel.
B. CO does not produce as much energy as would be in the case of CO2 formation in a combustion process.
a) Both statements are true
b) Both statements are false
c) A is correct and B is false
d) B is correct and A is false

Explanation: Statement I is correct for partial combustion and CO2 produces more energy than CO.

8. The amount of air required to be brought in to the process for complete combustion is
a) Theoretical Air
b) Excess Air
c) Partial Air
d) None of the mentioned

Explanation: The amount of air required to be brought in to the process for complete combustion is called Theoretical Air.

9. The amount of air in excess of the theoretical air required for complete combustion is
a) Theoretical Air
b) Excess Air
c) Partial Air
d) None of the mentioned

Explanation: The amount of air in excess of the theoretical air required for complete combustion is called Excess Air.

10. Ethane is burnt with 50% of excess air, what is the percentage of CO2 in the products?
a) 11.11%
b) 36.36%
c) 66.66%
d) 72.72%

Explanation: Percentage of CO2 = 20/55*100 = 36.36%.

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