5TH CLASS POWER ENGINEERING EXAM | COMPLETE EXAM QUESTIONS AND CORRECT
ANSWERS| 2026/2027 | NEWEST VERSION (PASS GUARANTEE)
POWER ENGINEERING 5TH CLASS EXAM
1. The efficiency of a Carnot cycle operating between temperatures of 800 K and 300
K is:
A. 37.5%
B. 62.5% ✓
C. 50.0%
D. 45.0%
2. In a steam power plant, the function of the condenser is to:
A. Increase steam pressure
B. Superheat the steam
C. Condense exhaust steam and maintain low back pressure ✓
D. Preheat feedwater
3. The first law of thermodynamics states that:
A. Heat cannot flow from cold to hot
B. Energy can be neither created nor destroyed ✓
C. Entropy always increases
D. All processes are reversible
4. In a Rankine cycle, the process in the boiler is:
A. Adiabatic compression
B. Isothermal expansion
C. Constant pressure heat addition ✓
D. Isentropic expansion
5. Superheat in steam refers to:
A. Steam above atmospheric pressure
, B. Steam heated beyond the saturation temperature at a given pressure ✓
C. Steam at critical pressure
D. Wet steam with high dryness fraction
6. The dryness fraction of wet steam is defined as:
A. Ratio of steam pressure to atmospheric pressure
B. Ratio of mass of dry steam to total mass of wet steam ✓
C. Ratio of latent heat to total heat
D. Ratio of steam temperature to saturation temperature
7. Which of the following is NOT a property of a pure substance?
A. Temperature
B. Pressure
C. Entropy
D. Velocity ✓
8. The second law of thermodynamics states:
A. Energy is conserved in all processes
B. It is impossible to construct a device that operates in a cycle and produces
no effect other than the transfer of heat from a cooler to a hotter body ✓
C. Work equals force times distance
D. Pressure and volume are directly proportional
9. Enthalpy is defined as:
A. H = U – PV
B. H = U + PV ✓
C. H = Q/T
D. H = W/Q
10. The critical point of water occurs at approximately:
A. 100°C and 101.3 kPa
B. 374°C and 22.1 MPa ✓
C. 200°C and 5 MPa
D. 300°C and 10 MPa
SECTION 2 — BOILERS
,11. A watertube boiler differs from a firetube boiler in that:
A. Hot gases pass through tubes surrounded by water
B. Water circulates through tubes while hot gases surround them ✓
C. It operates only at low pressures
D. It uses oil fuel exclusively
12. The purpose of a steam drum in a watertube boiler is:
A. To store feedwater
B. To separate steam from water and provide steam storage ✓
C. To superheat steam
D. To preheat combustion air
13. What is the purpose of a blowdown valve on a boiler?
A. To relieve excess pressure
B. To remove accumulated sludge and dissolved solids from the boiler water
✓
C. To add chemicals to the feedwater
D. To drain the condenser
14. The function of a safety valve on a boiler is:
A. To control operating pressure
B. To automatically relieve pressure if it exceeds the safe working limit ✓
C. To measure steam flow
D. To control feedwater level
15. A low water level alarm on a boiler is required to:
A. Alert operators when pressure drops
B. Alert operators when water level falls below a safe minimum to prevent
overheating ✓
C. Signal when blowdown is needed
D. Indicate scale buildup
16. The main purpose of economizers in a boiler system is to:
A. Reduce steam pressure
B. Recover heat from flue gases to preheat feedwater ✓
C. Superheat the steam
, D. Remove dissolved oxygen from feedwater
17. Scale formation in boiler tubes is primarily caused by:
A. High temperatures
B. Dissolved salts in feedwater that precipitate on heating ✓
C. Excess oxygen in the water
D. High steam pressures
18. A Scotch marine boiler is classified as a:
A. Watertube boiler
B. Firetube boiler with internal furnace ✓
C. Vertical boiler
D. Once-through boiler
19. The fusible plug in a boiler is located:
A. At the steam outlet
B. At the crown of the furnace or in a position that is normally covered by
water ✓
C. In the steam drum
D. At the feedwater inlet
20. Which type of boiler is most suitable for rapid steam generation?
A. Lancashire boiler
B. Scotch marine boiler
C. Watertube boiler ✓
D. Cornish boiler
SECTION 3 — STEAM TURBINES
21. In an impulse turbine, steam expansion occurs:
A. Entirely in the moving blades
B. Entirely in the stationary nozzles ✓
C. Equally in nozzles and blades
D. In the condenser
22. A reaction turbine differs from an impulse turbine because:
A. It uses higher pressure steam
ANSWERS| 2026/2027 | NEWEST VERSION (PASS GUARANTEE)
POWER ENGINEERING 5TH CLASS EXAM
1. The efficiency of a Carnot cycle operating between temperatures of 800 K and 300
K is:
A. 37.5%
B. 62.5% ✓
C. 50.0%
D. 45.0%
2. In a steam power plant, the function of the condenser is to:
A. Increase steam pressure
B. Superheat the steam
C. Condense exhaust steam and maintain low back pressure ✓
D. Preheat feedwater
3. The first law of thermodynamics states that:
A. Heat cannot flow from cold to hot
B. Energy can be neither created nor destroyed ✓
C. Entropy always increases
D. All processes are reversible
4. In a Rankine cycle, the process in the boiler is:
A. Adiabatic compression
B. Isothermal expansion
C. Constant pressure heat addition ✓
D. Isentropic expansion
5. Superheat in steam refers to:
A. Steam above atmospheric pressure
, B. Steam heated beyond the saturation temperature at a given pressure ✓
C. Steam at critical pressure
D. Wet steam with high dryness fraction
6. The dryness fraction of wet steam is defined as:
A. Ratio of steam pressure to atmospheric pressure
B. Ratio of mass of dry steam to total mass of wet steam ✓
C. Ratio of latent heat to total heat
D. Ratio of steam temperature to saturation temperature
7. Which of the following is NOT a property of a pure substance?
A. Temperature
B. Pressure
C. Entropy
D. Velocity ✓
8. The second law of thermodynamics states:
A. Energy is conserved in all processes
B. It is impossible to construct a device that operates in a cycle and produces
no effect other than the transfer of heat from a cooler to a hotter body ✓
C. Work equals force times distance
D. Pressure and volume are directly proportional
9. Enthalpy is defined as:
A. H = U – PV
B. H = U + PV ✓
C. H = Q/T
D. H = W/Q
10. The critical point of water occurs at approximately:
A. 100°C and 101.3 kPa
B. 374°C and 22.1 MPa ✓
C. 200°C and 5 MPa
D. 300°C and 10 MPa
SECTION 2 — BOILERS
,11. A watertube boiler differs from a firetube boiler in that:
A. Hot gases pass through tubes surrounded by water
B. Water circulates through tubes while hot gases surround them ✓
C. It operates only at low pressures
D. It uses oil fuel exclusively
12. The purpose of a steam drum in a watertube boiler is:
A. To store feedwater
B. To separate steam from water and provide steam storage ✓
C. To superheat steam
D. To preheat combustion air
13. What is the purpose of a blowdown valve on a boiler?
A. To relieve excess pressure
B. To remove accumulated sludge and dissolved solids from the boiler water
✓
C. To add chemicals to the feedwater
D. To drain the condenser
14. The function of a safety valve on a boiler is:
A. To control operating pressure
B. To automatically relieve pressure if it exceeds the safe working limit ✓
C. To measure steam flow
D. To control feedwater level
15. A low water level alarm on a boiler is required to:
A. Alert operators when pressure drops
B. Alert operators when water level falls below a safe minimum to prevent
overheating ✓
C. Signal when blowdown is needed
D. Indicate scale buildup
16. The main purpose of economizers in a boiler system is to:
A. Reduce steam pressure
B. Recover heat from flue gases to preheat feedwater ✓
C. Superheat the steam
, D. Remove dissolved oxygen from feedwater
17. Scale formation in boiler tubes is primarily caused by:
A. High temperatures
B. Dissolved salts in feedwater that precipitate on heating ✓
C. Excess oxygen in the water
D. High steam pressures
18. A Scotch marine boiler is classified as a:
A. Watertube boiler
B. Firetube boiler with internal furnace ✓
C. Vertical boiler
D. Once-through boiler
19. The fusible plug in a boiler is located:
A. At the steam outlet
B. At the crown of the furnace or in a position that is normally covered by
water ✓
C. In the steam drum
D. At the feedwater inlet
20. Which type of boiler is most suitable for rapid steam generation?
A. Lancashire boiler
B. Scotch marine boiler
C. Watertube boiler ✓
D. Cornish boiler
SECTION 3 — STEAM TURBINES
21. In an impulse turbine, steam expansion occurs:
A. Entirely in the moving blades
B. Entirely in the stationary nozzles ✓
C. Equally in nozzles and blades
D. In the condenser
22. A reaction turbine differs from an impulse turbine because:
A. It uses higher pressure steam
