Question

carbon _________ is a colorless, odorless, and poisonous gas.

a monoxide
b dioxide
c trioxide

Explanation:

Analyze the question stem

The question asks to identify a specific compound of carbon that is a colorless, odorless, and poisonous gas.

Evaluate the options

• Carbon monoxide (\(\text{CO}\)) is a highly toxic, colorless, and odorless gas. It binds strongly to hemoglobin in red blood cells, preventing oxygen transport.
• Carbon dioxide (\(\text{CO}_2\)) is colorless and odorless, but it is not classified as a poisonous gas under normal conditions (though it is an asphyxiant at very high concentrations).
• Carbon trioxide (\(\text{CO}_3\)) is an unstable oxide of carbon that does not exist as a stable gas under standard conditions.

Determine the correct answer

Based on the chemical properties, carbon monoxide perfectly matches the description of being a colorless, odorless, and poisonous gas.

Answer:

• a monoxide (Correct answer)
• b dioxide
• c trioxide