CFESA GAS REVIEW QUESTIONS WITH 100%
CORRECT AND VERIFIED ANSWERS 2025
Why is LP gas more DANGEROUS to work with than natural gas?
CORRECT ANSWER ✓ ✓ LP is heavier than air so it does not dissipate, and is more
volatile Rationale: Traps in low spots = explosion risk. Natural floats away.
Carbon monoxide is being produced – will there be aldehydes?
CORRECT ANSWER ✓ ✓ No, not always Rationale: CO = silent killer. Aldehydes = stinky
warning. Not guaranteed together.
There are aldehydes – is carbon monoxide present?
CORRECT ANSWER ✓ ✓ yes Rationale: Pungent smell = incomplete burn = CO likely
lurking. Test NOW.
LP tanks filled with gas or liquid?
CORRECT ANSWER ✓ ✓ Liquid Rationale: Liquid boils to gas as you use it – 270x
expansion = massive power.
One cubic foot of natural gas needs how much air to burn clean?
CORRECT ANSWER ✓ ✓ minimum of 10 Rationale: Too little = CO & soot. Too much =
wasted heat. 10:1 = perfect blue flame.
,Where does natural gas come from?
CORRECT ANSWER ✓ ✓ Wells deep in the ground Rationale: Drilled from underground
reservoirs, cleaned and piped to homes.
Where does LP gas come from?
CORRECT ANSWER ✓ ✓ byproduct of crude oil, and some is from natural gas pockets
Rationale: Refinery byproduct or extracted during natural gas processing.
What are the three different gases often termed as LP gas?
CORRECT ANSWER ✓ ✓ butane, ethane, propane Rationale: All liquefy under pressure;
propane most common for cooking.
What happens in a LP tank as gas is drawn off?
CORRECT ANSWER ✓ ✓ The liquid boils off and creates additional gas. Rationale:
Vaporization replaces used gas to maintain pressure.
Does natural gas have any odor?
CORRECT ANSWER ✓ ✓ No, not when it comes from the ground and is cleaned
Rationale: Mercaptan added later for leak detection.
What is meant by the "specific gravity" of as gas?
CORRECT ANSWER ✓ ✓ the weight of gas compared to the weight of air Rationale:
Determines if gas rises (lighter) or sinks (heavier) in air.
Is natural gas heavier or lighter than air?
, CORRECT ANSWER ✓ ✓ Lighter Rationale: Specific gravity ~0.6; rises and disperses
quickly.
Is LP gas heavier or lighter than air?
CORRECT ANSWER ✓ ✓ Heavier Rationale: Specific gravity ~1.5–2.0; pools in low areas.
What is the heating value of a cubic foot of natural gas?
CORRECT ANSWER ✓ ✓ Approx. 1000 Btu/cu. ft. Varies from 950 to 1150 btus
Rationale: Energy output per volume; varies by gas composition.
What is the heating value for LP gas?
CORRECT ANSWER ✓ ✓ 2500 Btu/cu. ft. Rationale: 2.5x more energy-dense than
natural gas.
How should you check for gas leaks?
CORRECT ANSWER ✓ ✓ Soap bubbles or electronic leak detector Rationale: Safe,
reliable methods; never use flame.
Which gas is more volatile, natural or LP gas? Why?
CORRECT ANSWER ✓ ✓ LP, it has a higher Btu rating per cubic foot, and is heavier than
air so it does not dissipate. Rationale: Higher energy + pooling = greater fire/explosion
risk.
What are 3 things needed for combustion?
CORRECT ANSWER ✓ ✓ fuel, oxygen, heat Rationale: The fire triangle; remove any one
to stop burning.
CORRECT AND VERIFIED ANSWERS 2025
Why is LP gas more DANGEROUS to work with than natural gas?
CORRECT ANSWER ✓ ✓ LP is heavier than air so it does not dissipate, and is more
volatile Rationale: Traps in low spots = explosion risk. Natural floats away.
Carbon monoxide is being produced – will there be aldehydes?
CORRECT ANSWER ✓ ✓ No, not always Rationale: CO = silent killer. Aldehydes = stinky
warning. Not guaranteed together.
There are aldehydes – is carbon monoxide present?
CORRECT ANSWER ✓ ✓ yes Rationale: Pungent smell = incomplete burn = CO likely
lurking. Test NOW.
LP tanks filled with gas or liquid?
CORRECT ANSWER ✓ ✓ Liquid Rationale: Liquid boils to gas as you use it – 270x
expansion = massive power.
One cubic foot of natural gas needs how much air to burn clean?
CORRECT ANSWER ✓ ✓ minimum of 10 Rationale: Too little = CO & soot. Too much =
wasted heat. 10:1 = perfect blue flame.
,Where does natural gas come from?
CORRECT ANSWER ✓ ✓ Wells deep in the ground Rationale: Drilled from underground
reservoirs, cleaned and piped to homes.
Where does LP gas come from?
CORRECT ANSWER ✓ ✓ byproduct of crude oil, and some is from natural gas pockets
Rationale: Refinery byproduct or extracted during natural gas processing.
What are the three different gases often termed as LP gas?
CORRECT ANSWER ✓ ✓ butane, ethane, propane Rationale: All liquefy under pressure;
propane most common for cooking.
What happens in a LP tank as gas is drawn off?
CORRECT ANSWER ✓ ✓ The liquid boils off and creates additional gas. Rationale:
Vaporization replaces used gas to maintain pressure.
Does natural gas have any odor?
CORRECT ANSWER ✓ ✓ No, not when it comes from the ground and is cleaned
Rationale: Mercaptan added later for leak detection.
What is meant by the "specific gravity" of as gas?
CORRECT ANSWER ✓ ✓ the weight of gas compared to the weight of air Rationale:
Determines if gas rises (lighter) or sinks (heavier) in air.
Is natural gas heavier or lighter than air?
, CORRECT ANSWER ✓ ✓ Lighter Rationale: Specific gravity ~0.6; rises and disperses
quickly.
Is LP gas heavier or lighter than air?
CORRECT ANSWER ✓ ✓ Heavier Rationale: Specific gravity ~1.5–2.0; pools in low areas.
What is the heating value of a cubic foot of natural gas?
CORRECT ANSWER ✓ ✓ Approx. 1000 Btu/cu. ft. Varies from 950 to 1150 btus
Rationale: Energy output per volume; varies by gas composition.
What is the heating value for LP gas?
CORRECT ANSWER ✓ ✓ 2500 Btu/cu. ft. Rationale: 2.5x more energy-dense than
natural gas.
How should you check for gas leaks?
CORRECT ANSWER ✓ ✓ Soap bubbles or electronic leak detector Rationale: Safe,
reliable methods; never use flame.
Which gas is more volatile, natural or LP gas? Why?
CORRECT ANSWER ✓ ✓ LP, it has a higher Btu rating per cubic foot, and is heavier than
air so it does not dissipate. Rationale: Higher energy + pooling = greater fire/explosion
risk.
What are 3 things needed for combustion?
CORRECT ANSWER ✓ ✓ fuel, oxygen, heat Rationale: The fire triangle; remove any one
to stop burning.
