You're in Europe!
Gas! Gas! Gas!
Sounds the Same
I Feel Like Such a Idiom!
100
This country is home to the Eiffel Tower, the Louvre Museum, and croissants.
What is France? 
100
Hank Hill knows it’s the most common liquefied petroleum gas used in North American homes.
What is propane?
100
Having knowledge, or a pair of the letter after X.
What is wise/Y’s?
100
An enthusiastic, hard worker is often compared to this zealous rodent.
What is an eager beaver?
200
The world's earliest steam locomotives pulled cars filled with this product out of mines in Wales.
What is coal?
200
After the Hindenburg disaster, modern non-rigid airships began using helium in place of this explosive gas.
What is hydrogen?
200
Feeble, or seven days.
What is weak/week?
200
On April 14, 1865, John Wilkes Booth must have taken literally this three-word phrase actors use to mean "good luck."
What is break a leg?
300
The Matterhorn, one of the most photographed mountains in the world, sits on the border of Italy and this country.
What is Switzerland? 
300
Used in World War I and against Iraq's Kurds, this gas is named for its distinctive smell.
What is mustard gas?
300
Reasonable, or a payment for travel.
What is fair/fare?
300
Meaning “to quiet down,” this phrase comes from the practice of stuffing a stocking into a gramophone to lower the volume.
What is put a sock in it?
400
Bulgaria is a leading producer of attar, an oil distilled from these flowers.
What are roses?
400
The atmosphere of Venus, the heaviest of any planet, is mainly composed of this common gas, which is 1.5 times heavier than air.
What is carbon dioxide?
400
To find and dig out this metal-containing material with this boating implement would be a stroke of luck.
What is ore/oar?
400
This two-word term refers to an "arboreal" diagram showing family relationships.
What is a family tree?
500
In 1997, this Eastern European country restored the citizenship of its exiled King Michael.
What is Romania?
500
Deep sea divers must carefully decompress to prevent gas bubbles of this element from forming in the body.
What is nitrogen?
500
Your lips may say "No, no, no," but these say "Yes, yes, yes."
What are eyes/ayes?
500
To "machine gun the zephyr" is a literal way of saying this phrase meaning to chat aimlessly.
What is shoot the breeze?