250+ TOP MCQs on Simplifications of General Energy Balance and Answers

Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) on “Simplifications of General Energy Balance”.

1. What is the work done by an open steady-state system if heat transferred to it is 10 J?
a) 0
b) -10 J
c) 10 J
d) Cannot be determined

Answer: c
Clarification: In steady state system ∆E = 0, => Work done by the system = 10 J.

2. In a closed system, change in internal energy is 10 J and heat transferred to it is 10 J what is the work done by the system?
a) 0
b) 10 J
c) -20 J
d) 20 J

Answer: a
Clarification: ∆E = W + Q, => W = 10 – 10 = 0.

3. In an open system, what is the enthalpy change is heat taken from it is 10 J?
a) 0
b) -10 J
c) 10 J
d) Cannot be determined

Answer: b
Clarification: For an open system, ∆H = Q, => ∆H = -10 J.

4. In an open, steady state adiabatic process if the change in kinetic energy is 10 J and change in potential energy is 15 J, what is the work done by the system?
a) 10 J
b) 15 J
c) 25 J
d) -25 J

Answer: d
Clarification: -W = ∆KE + ∆PE = 10 + 15 = 25, => W = -25 J.

5. In an open, steady state system if the heat transferred is 10 J and work done by the system is 5 J, what is the change in Potential energy (neglect kinetic energy)?
a) 5 J
b) -5J
c) 15 J
d) -15 J

Answer: a
Clarification: W + Q = ∆PE, => ∆PE = 10 – 5 = 5 J.

6. Which of the following is true for isothermal ideal gases?
a) ∆T = 0
b) ∆U = 0
c) ∆H = 0
d) All of the mentioned

Answer: d
Clarification: For isothermal ideal gases, ∆T = 0, => ∆U = 0, => ∆H = 0.

7. If the system is insulated which of the following might the process be?
a) Isothermal
b) Isobaric
c) Isochoric
d) Adiabatic

Answer: d
Clarification: Since the system is insulated, => Q = 0, => Process is adiabatic.

8. What is the work done for an isochoric process?
a) Positive
b) Negative
c) Zero
d) Cannot say

Answer: c
Clarification: W = -PdV, for isochoric process dV = 0, => W = 0.

9. What is the work done for an ideal gas isothermal process?
a) Zero
b) Equal to heat transferred
c) Equal to change in internal energy
d) Cannot say

Answer: b
Clarification: For ideal gas isothermal process ∆U = 0, => Work done is equal to heat transferred.

10. What is the work done for an isobaric process?
a) P∆V
b) V∆P
c) PV
d) None of the mentioned

Answer: a
Clarification: For isobaric process ∆P = 0, => W = P∆V.

11. For an ideal gas isobaric process at pressure 1 Pa, the volume of the gas changes from 1 m³ to 5 m³, what is the work done by the gas?
a) 1 J
b) 4 J
c) 5 J
d) 10 J

Answer: b
Clarification: W = P∆V = 1*(5 – 1) = 4 J.

12. For an ideal gas isothermal process what is the work done by the gas from 1 m³ to 2 m³ at 300 K?
a) 0.69 kJ
b) 1.24 kJ
c) 1.73 kJ
d) 2.45 kJ

Answer: c
Clarification: W = RTln (V₂/V₁) = 8.314*300 ln (2/1) = 1.73 kJ.

13. For an ideal gas isothermal process what is the work done by the gas from 4 Pa to 1 Pa at 300 K?
a) 1.22 kJ
b) 2.15 kJ
c) 2.83 kJ
d) 3.45 kJ

Answer: d
Clarification: W = RTln (P₁/P₂) = 8.314*300 ln (4/1) = 3.45 kJ.

14. For an ideal gas isochoric process, what is the work done by the gas from 2 Pa to 1 Pa?
a) 0
b) 1 J
c) 200 J
d) None of the mentioned

Answer: a
Clarification: Since the process is isochoric, => W = 0.

15. For an ideal gas isobaric process what is the work done by the gas from 2 m³ to 0.5 m³ at 2 Pa?
a) -3 J
b) 3 J
c) -5 J
d) 5 J

Answer: a
Clarification: Work done by the gas = 2*(0.5 – 2) = -3 J.