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Multiple choice question for engineering

Set 1

1-7. For the given reaction
C5H12 + 8 O2 → 5 CO2 + 6 H2O
If the reactants C5H12 & O2 are having 2 moles an 8 moles of initial feed respectively.
1. Which is the excess reactant in the reaction?
a) C5H12
b) O2
c) CO2
d) H2O

View Answer

Answer: a [Reason:] C5H12 is the excess reactant as 1 mole of C5H12 = 8 moles of CO2.

2. Which is the limiting reactant in the reaction?
a) C5H12
b) O2
c) CO2
d) H2O

View Answer

Answer: b [Reason:] O2 is the limiting reactant as 1 mole of C5H12 = 8 moles of CO2.

3. How many moles of C5H12 are there when the reaction completes?
a) 0
b) 1
c) 2
d) 3

View Answer

Answer: b [Reason:] Moles left = Initial mole – extent of the reaction*stoichiometric coefficient.

4. How many moles of O2 are there when the reaction completes?
a) 0
b) 2
c) 4
d) 6

View Answer

Answer: a [Reason:] Moles left = Initial mole – extent of the reaction*stoichiometric coefficient.

5. How many moles of CO2 produced in the reaction?
a) 5
b) 6
c) 7
d) 8

View Answer

Answer: a [Reason:] Moles produced = extent of the reaction*Stoichiometric coefficient.

6. How many moles of H2O produced in the reaction?
a) 5
b) 6
c) 7
d) 8

View Answer

Answer: b [Reason:] Moles produced = extent of the reaction*Stoichiometric coefficient.

7. What is the extent of the reaction?
a) 0
b) 1
c) 2
d) 3

View Answer

Answer: b [Reason:] Extent of the reaction = (Initial moles – Final moles) / Stoichiometric coefficient.

8-10. For the given reaction
CO2 + 4 H → CH2O + H2O
In the feed there are 4 moles of CO2, 10 moles of H. If the reaction happens then
8. What is the number of moles of the extent reactant in the reaction after completion?
a) 0
b) 1
c) 1.5
d) 2.5

View Answer

Answer: c [Reason:] Number of moles of CO2 left = 4 – 2.5 = 1.5.

9. What is the extent of the reaction?
a) 0
b) 1
c) 1.5
d) 2.5

View Answer

Answer: d [Reason:] Extent of the reaction = (Initial moles – Final moles) / Stoichiometric coefficient.

10. What is the gms of CO2 produced in the reaction?
a) 0
b) 1
c) 1.5
d) 2.5

View Answer

Answer: d [Reason:] Moles of CO2 produced = 2.5 = Extent of the reaction.

Set 2

1. In Langmuir’s model of adsorption of a gas on a solid surface the mass of gas striking a given area of surface is ______________to the pressure of the gas.
a) Proportional
b) Anti proportional
c) Independent
d) None of the mentioned

View Answer

Answer: a [Reason:] In Langmuir’s model of adsorption of a gas on a solid surface the mass of gas striking a given area of surface is proportional to the pressure of the gas.

2. Physical adsorption increase with _________ in temperature.
a) Increase
b) Decrease
c) Neither increase nor decrease
d) None of the mentioned

View Answer

Answer: b [Reason:] Physical adsorption increase with decrease in temperature.

3. The physical process that occurs when gas or liquid molecules are brought into contact with a solid surface and condense on the surface
a) Absorption
b) Adsorption
c) Both Adsorption and Absorption
d) None of the mentioned

View Answer

Answer: b [Reason:] Adsorption is the physical process that occurs when gas or liquid molecules are brought into contact with a solid surface and condense on the surface.

4. Adsorbent is a solid surface on which gas or liquid molecules condense to form a film.
The above given statement is
a) Correct
b) Incorrect
c) Partially correct
d) None of the mentioned

View Answer

Answer: a [Reason:] Adsorbent is a solid surface on which gas or liquid molecules condense to form a film.

5. Adsorption when interaction between the solid and the condensed molecules is relatively strong as contrasted with physical adsorption.
a) Absorption
b) Adsorption
c) Chemisorption
d) None of the mentioned

View Answer

Answer: b [Reason:] “Chemisorption is the adsorption when interaction between the solid and the condensed molecules is relatively strong as contrasted with physical adsorption.

6. The gas molecules are held on solid surface by _________ in physical adsorption.
a) Chemical forces
b) Gravitational forces
c) Electrostatic forces
d) Vander Waal’s forces

View Answer

Answer: d [Reason:] Chemisorption is the adsorption when interaction between the solid and the condensed molecules is relatively strong as contrasted with physical adsorption.

7. The extent of adsorption of a gas on a solid depend on
a) Nature of gas
b) Pressure of gas
c) Temperature of the system
d) All of the mentioned

View Answer

Answer: d [Reason:] The extent of adsorption of a gas on a solid depend on all three nature of gas, pressure of gas and temperature of the system.

8. Which of the following gases is adsorbed by charcoal?
a) NH3
b) H2
c) N2
d) CO2

View Answer

Answer: a [Reason:] NH3 is easily liquefiable and highly water soluble gas.

9. Langmuir isotherm Mathematical relation for ___________ that takes place at equilibrium.
a) Absorption
b) Adsorption
c) Both Adsorption and Absorption
d) None of the mentioned

View Answer

Answer: b [Reason:] Langmuir isotherm Mathematical relation for adsorption that takes place at equilibrium.

10. Adsorption process must be
a) Endoethrgic
b) Endothermic
c) Exothermic
d) None

View Answer

Answer: c [Reason:] Adsorption process is an Exothermic process.

Set 3

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%

View Answer

Answer: a [Reason:] 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

View Answer

Answer: d [Reason:] 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

View Answer

Answer: a [Reason:] 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%

View Answer

Answer: d [Reason:] 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

View Answer

Answer: c [Reason:] All the gases resulting from a combustion process, not including the water vapour is known as Orsat analysis.

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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: b [Reason:] 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%

View Answer

Answer: b [Reason:] Percentage of CO2 = 20/55*100 = 36.36%.

Set 4

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%

View Answer

Answer: a [Reason:] 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

View Answer

Answer: d [Reason:] 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

View Answer

Answer: a [Reason:] 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%

View Answer

Answer: d [Reason:] 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

View Answer

Answer: c [Reason:] All the gases resulting from a combustion process, not including the water vapour is known as Orsat analysis.

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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: b [Reason:] 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%

View Answer

Answer: b [Reason:] Percentage of CO2 = 20/55*100 = 36.36%.

Set 5

1. Material balance equation can be applied to
a) Total mass
b) Mass of a component
c) Moles of a component
d) All of the mentioned

View Answer

Answer: d [Reason:] Material balance equation can be applied to all these as these are conserved under every change in a chemical process.

2. Material balance equation cannot be applied to
a) Total moles
b) Mass of an atomic species
c) Moles of an atomic species
d) All of the mentioned

View Answer

Answer: a [Reason:] Total moles may vary.

3. We don`t use volume balance in a chemical process because
a) Mass is not conserved in a process
b) Volume is not conserved in a process
c) Both a and b
d) Neither a nor b

View Answer

Answer: b [Reason:] Volume is not conserved in a process because different materials have different densities.

4. In the given tank, there are two feeds and one output. Consider a 2 hour operation; the feed rates are 4000 kg/hr and 6000 kg/hr. The accumulated material inside the tank is 2000 kg. What is the output rate kg/hr of the material?
a) 9000
b) 8000
c) 7000
d) 6000

View Answer

Answer: a [Reason:] Input = output, Take a basis: 2 hour.

5. In a process the inputs and outputs are shown as in the diagram
chemical-process-calculation-questions-answers-material-balances-i-q5
Correct material balance is
a) B+C = A+D
b) A+B = C+D
c) A+C = B+D
d) None of the mentioned

View Answer

Answer: a [Reason:] What comes in, goes out.

6. Based on number of degrees of freedom, find the incorrect statement, consider
NU = Number of unknown
NE = Number of unknown equation
a) NU = NE for that a solution
b) NU > NE > 0 for that more independent equation required
c) NU< NE < 0 for that no solution exists unless some constraints are eliminated
d) None of the mentioned

View Answer

Answer: d [Reason:] ND = NU – NE Where: ND = Number of degrees of freedom.

7. In a process, two feed streams are there and one output stream. The feed streams have the feed rates as 500 kg/sec and 600 kg/sec. If the output stream rate is 800 kg/s, what is the mass stored in the chamber in five seconds?
a) 300 kg
b) 500 kg
c) 1000 kg
d) 1500 kg

View Answer

Answer: d [Reason:] For five seconds, Accumulation = 5(500+600-800) Kg.

8 – 10. For the given steady state system, consider that a unique solution exists for the process.
ω1, ω2, ω3 are the mass fractions of the components 1, 2 and 3.
chemical-process-calculation-questions-answers-material-balances-i-q8

8. What is the value of ω2 for A?
a) 0.5
b) 0.6
c) 0.7
d) 0.8

View Answer

Answer: a [Reason:] Σω = 1.

9. What ids the value of ω2 for P?
a) 0.98
b) 0.88
c) 0.78
d) 0.68

View Answer

Answer: d [Reason:] ω2F + ω2A = ω2P.

10. What ids the value of ω3 for P?
a) 0.09
b) 0.08
c) 0.07
d) 0.06

View Answer

Answer: b [Reason:] ω3A = ω3P.