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(P-2) Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A| Instant
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1. What is the primary purpose of a backflow preventer in a plumbing
system?
A) Increase water pressure
B) Prevent water contamination
C) Reduce water flow
D) Filter sediments
B) Prevent water contamination
Rationale: A backflow preventer is designed to stop contaminated water
from flowing back into the potable water supply, protecting public health.
2. Which type of pipe is most suitable for high-temperature water
distribution?
A) PVC
B) CPVC
C) PEX
D) ABS
B) CPVC
Rationale: CPVC (Chlorinated Polyvinyl Chloride) can withstand higher
temperatures than regular PVC, making it suitable for hot water systems.
, 3. What is the minimum slope required for a horizontal sanitary drainage
pipe?
A) 1/16 inch per foot
B) 1/8 inch per foot
C) 1/4 inch per foot
D) 1/2 inch per foot
C) 1/4 inch per foot
Rationale: A minimum slope of 1/4 inch per foot ensures adequate
drainage by gravity, preventing blockages.
4. In a residential water supply system, which valve is used to isolate
water flow to specific fixtures?
A) Check valve
B) Gate valve
C) Pressure-reducing valve
D) Relief valve
B) Gate valve
Rationale: Gate valves are commonly used to isolate sections of a water
system, allowing maintenance without shutting off the entire supply.
5. What is the maximum allowable water temperature for residential
plumbing fixtures?
A) 50°C (122°F)
B) 60°C (140°F)
C) 70°C (158°F)
D) 80°C (176°F)
B) 60°C (140°F)
Rationale: Most plumbing codes limit water heater output to 60°C to
prevent scalding while ensuring safety and comfort.
6. Which method is commonly used to join copper pipes in plumbing?
A) Threading
B) Solvent welding
C) Soldering
D) Compression
, C) Soldering
Rationale: Soldering is a standard method for joining copper pipes,
providing a watertight seal when done correctly.
7. What is the purpose of a vent pipe in a drainage system?
A) To increase water pressure
B) To allow air circulation and prevent siphoning
C) To filter debris from water
D) To heat water in winter
B) To allow air circulation and prevent siphoning
Rationale: Vent pipes maintain proper pressure in the drainage system and
prevent traps from being siphoned dry.
8. Which type of valve allows flow in only one direction?
A) Ball valve
B) Gate valve
C) Check valve
D) Globe valve
C) Check valve
Rationale: Check valves prevent backflow, ensuring water flows in only one
direction.
9. What is the typical pipe size for a residential water supply to a single
fixture?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1 1/2 inches
A) 1/2 inch
Rationale: A 1/2-inch pipe is standard for supplying water to individual
fixtures, balancing flow and cost efficiency.
10. Which material is commonly used for underground drainage
systems?
A) PVC
(P-2) Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A| Instant
Download Pdf
1. What is the primary purpose of a backflow preventer in a plumbing
system?
A) Increase water pressure
B) Prevent water contamination
C) Reduce water flow
D) Filter sediments
B) Prevent water contamination
Rationale: A backflow preventer is designed to stop contaminated water
from flowing back into the potable water supply, protecting public health.
2. Which type of pipe is most suitable for high-temperature water
distribution?
A) PVC
B) CPVC
C) PEX
D) ABS
B) CPVC
Rationale: CPVC (Chlorinated Polyvinyl Chloride) can withstand higher
temperatures than regular PVC, making it suitable for hot water systems.
, 3. What is the minimum slope required for a horizontal sanitary drainage
pipe?
A) 1/16 inch per foot
B) 1/8 inch per foot
C) 1/4 inch per foot
D) 1/2 inch per foot
C) 1/4 inch per foot
Rationale: A minimum slope of 1/4 inch per foot ensures adequate
drainage by gravity, preventing blockages.
4. In a residential water supply system, which valve is used to isolate
water flow to specific fixtures?
A) Check valve
B) Gate valve
C) Pressure-reducing valve
D) Relief valve
B) Gate valve
Rationale: Gate valves are commonly used to isolate sections of a water
system, allowing maintenance without shutting off the entire supply.
5. What is the maximum allowable water temperature for residential
plumbing fixtures?
A) 50°C (122°F)
B) 60°C (140°F)
C) 70°C (158°F)
D) 80°C (176°F)
B) 60°C (140°F)
Rationale: Most plumbing codes limit water heater output to 60°C to
prevent scalding while ensuring safety and comfort.
6. Which method is commonly used to join copper pipes in plumbing?
A) Threading
B) Solvent welding
C) Soldering
D) Compression
, C) Soldering
Rationale: Soldering is a standard method for joining copper pipes,
providing a watertight seal when done correctly.
7. What is the purpose of a vent pipe in a drainage system?
A) To increase water pressure
B) To allow air circulation and prevent siphoning
C) To filter debris from water
D) To heat water in winter
B) To allow air circulation and prevent siphoning
Rationale: Vent pipes maintain proper pressure in the drainage system and
prevent traps from being siphoned dry.
8. Which type of valve allows flow in only one direction?
A) Ball valve
B) Gate valve
C) Check valve
D) Globe valve
C) Check valve
Rationale: Check valves prevent backflow, ensuring water flows in only one
direction.
9. What is the typical pipe size for a residential water supply to a single
fixture?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1 1/2 inches
A) 1/2 inch
Rationale: A 1/2-inch pipe is standard for supplying water to individual
fixtures, balancing flow and cost efficiency.
10. Which material is commonly used for underground drainage
systems?
A) PVC
