27 real Material & Energy Balance questions from the Chemical Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Limiting reactant?
Junior
A.reactant present in the smallest stoichiometric proportion, fully consumed if the reaction goes to completion and fixing the theoretical yield
B.chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
C.outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
D.small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
2. Which term means: "reactant present in the smallest stoichiometric proportion, fully consumed if the reaction goes to completion and fixing the theoretical yield"?
A.Limiting reactant — reactant present in the smallest stoichiometric proportion, fully consumed if the reaction goes to completion and fixing the theoretical yield
B.Limiting reactant — count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
C.Limiting reactant — standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
D.Limiting reactant — chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
A.Degree of freedom analysis — chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
B.Degree of freedom analysis — substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
C.Degree of freedom analysis — standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
D.Degree of freedom analysis — count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
A.overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower
B.reactant present in the smallest stoichiometric proportion, fully consumed if the reaction goes to completion and fixing the theoretical yield
C.outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
D.chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
A.Basis of calculation — outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
B.Basis of calculation — small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
C.Basis of calculation — standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
D.Basis of calculation — chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
A.overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower
B.outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
C.small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
D.substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
11. Which term means: "substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses"?
A.Tie component — overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower
B.Tie component — standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
C.Tie component — chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
D.Tie component — substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
A.standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
B.count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
C.substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
D.small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
14. Which term means: "small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process"?
A.Purge stream — small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
B.Purge stream — overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower
C.Purge stream — count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
D.Purge stream — outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
17. Which term means: "overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower"?
A.Overall vs single-pass conversion — dry-basis volumetric flue-gas analysis of CO2, O2 and CO used to back-calculate excess air and completeness of combustion
B.Overall vs single-pass conversion — reactant present in the smallest stoichiometric proportion, fully consumed if the reaction goes to completion and fixing the theoretical yield
C.Overall vs single-pass conversion — overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower
D.Overall vs single-pass conversion — substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
A.substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
B.count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
C.overall is based on fresh feed to the process; single-pass is based on total reactor inlet including recycle and is always lower
D.standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
20. Which term means: "standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients"?
A.Heat of reaction from formation data — substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
B.Heat of reaction from formation data — outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
C.Heat of reaction from formation data — dry-basis volumetric flue-gas analysis of CO2, O2 and CO used to back-calculate excess air and completeness of combustion
D.Heat of reaction from formation data — standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
A.chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
B.outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
C.standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
D.small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
23. Which term means: "outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals"?
A.Adiabatic flame temperature — small bleed from a recycle loop that stops inerts or by-products accumulating, sized by an inert balance around the whole process
B.Adiabatic flame temperature — outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
C.Adiabatic flame temperature — chosen reference quantity such as 100 kg feed or one hour of operation on which all stream flows are computed and later scaled
D.Adiabatic flame temperature — dry-basis volumetric flue-gas analysis of CO2, O2 and CO used to back-calculate excess air and completeness of combustion
A.dry-basis volumetric flue-gas analysis of CO2, O2 and CO used to back-calculate excess air and completeness of combustion
B.count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
C.substance that passes unchanged through a unit, like nitrogen in air or ash in coal, used to relate inlet and outlet stream masses
D.outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
A.Orsat analysis — standard heat of reaction equals the sum of product formation enthalpies minus reactant formation enthalpies, weighted by stoichiometric coefficients
B.Orsat analysis — count of unknowns minus independent equations for a balance problem; zero means solvable, positive means under-specified
C.Orsat analysis — outlet temperature reached when all combustion heat goes into the product gases with no losses, found from an energy balance with sensible-heat integrals
D.Orsat analysis — dry-basis volumetric flue-gas analysis of CO2, O2 and CO used to back-calculate excess air and completeness of combustion
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