ONTARIO GAS TECHNICIAN 1 (G1) CERTIFICATION
EXAM QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) Q&A 2026 |INSTANT
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1. Which gas has the highest Lower Explosive Limit (LEL)?
A. Propane
B. Natural Gas
C. Hydrogen
D. Carbon Monoxide
Correct: A. Propane
Rationale: Propane’s LEL (~2.1%) is higher than natural gas
(~5%), meaning it takes more concentration to ignite.
2. An increase in oxygen concentration in a combustion
reaction generally causes:
A. Lower flame temperature
B. Higher combustion efficiency
C. More incomplete combustion
D. Reduced CO₂ output
Correct: B. Higher combustion efficiency
Rationale: More oxygen improves fuel oxidation, reducing
unburned products.
3. Which gas is lighter than air?
A. Propane
B. Butane
, C. Methane
D. Hexane
Correct: C. Methane
Rationale: Methane has a specific gravity <1 (about 0.55)
so it rises.
4. The theoretical amount of air required to completely
burn a fuel is called:
A. Actual air
B. Excess air
C. Stochiometric air
D. Enriched air
Correct: C. Stochiometric air
Rationale: This is the exact amount for complete
combustion.
5. Incomplete combustion may produce:
A. CO₂ and H₂O only
B. CO and soot
C. N₂ and O₂
D. CH₄
Correct: B. CO and soot
Rationale: Lack of sufficient oxygen leads to carbon
monoxide and unburned carbon.
6. Specific gravity of natural gas is important because it
determines:
A. Corrosivity
B. Heating value
, C. Flow rate
D. Leak behavior
Correct: D. Leak behavior
Rationale: Lighter gas disperses upward; heavier gases
accumulate low.
7. Which component dominates natural gas composition?
A. Ethane
B. Propane
C. Methane
D. Butane
Correct: C. Methane
Rationale: Methane typically makes up 70–90% of NG.
8. Upper Explosive Limit (UEL) refers to:
A. Minimum oxygen needed
B. Maximum fuel concentration for combustion
C. Optimal flame temperature
D. Minimum ignition energy
Correct: B. Maximum fuel concentration for combustion
Rationale: Above UEL mixtures are too rich to burn.
9. Complete combustion produces primarily:
A. CO and water
B. CO₂ and water
C. O₂ and soot
D. N₂ and fuel
Correct: B. CO₂ and water
Rationale: Ideal combustion oxidizes fuel fully.
EXAM QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) Q&A 2026 |INSTANT
DOWNLOAD PDF
1. Which gas has the highest Lower Explosive Limit (LEL)?
A. Propane
B. Natural Gas
C. Hydrogen
D. Carbon Monoxide
Correct: A. Propane
Rationale: Propane’s LEL (~2.1%) is higher than natural gas
(~5%), meaning it takes more concentration to ignite.
2. An increase in oxygen concentration in a combustion
reaction generally causes:
A. Lower flame temperature
B. Higher combustion efficiency
C. More incomplete combustion
D. Reduced CO₂ output
Correct: B. Higher combustion efficiency
Rationale: More oxygen improves fuel oxidation, reducing
unburned products.
3. Which gas is lighter than air?
A. Propane
B. Butane
, C. Methane
D. Hexane
Correct: C. Methane
Rationale: Methane has a specific gravity <1 (about 0.55)
so it rises.
4. The theoretical amount of air required to completely
burn a fuel is called:
A. Actual air
B. Excess air
C. Stochiometric air
D. Enriched air
Correct: C. Stochiometric air
Rationale: This is the exact amount for complete
combustion.
5. Incomplete combustion may produce:
A. CO₂ and H₂O only
B. CO and soot
C. N₂ and O₂
D. CH₄
Correct: B. CO and soot
Rationale: Lack of sufficient oxygen leads to carbon
monoxide and unburned carbon.
6. Specific gravity of natural gas is important because it
determines:
A. Corrosivity
B. Heating value
, C. Flow rate
D. Leak behavior
Correct: D. Leak behavior
Rationale: Lighter gas disperses upward; heavier gases
accumulate low.
7. Which component dominates natural gas composition?
A. Ethane
B. Propane
C. Methane
D. Butane
Correct: C. Methane
Rationale: Methane typically makes up 70–90% of NG.
8. Upper Explosive Limit (UEL) refers to:
A. Minimum oxygen needed
B. Maximum fuel concentration for combustion
C. Optimal flame temperature
D. Minimum ignition energy
Correct: B. Maximum fuel concentration for combustion
Rationale: Above UEL mixtures are too rich to burn.
9. Complete combustion produces primarily:
A. CO and water
B. CO₂ and water
C. O₂ and soot
D. N₂ and fuel
Correct: B. CO₂ and water
Rationale: Ideal combustion oxidizes fuel fully.
