G2 Gas Fitter Practice Exam

Which gas is generally odorless before the addition of mercaptan?

1. Propane

2. Natural gas

3. Butane

4. Methane

The correct answer is: Natural gas

Natural gas is generally considered odorless before the addition of mercaptan, which is a chemical that imparts a distinctive smell to help identify gas leaks. This safety measure is crucial because natural gas is a significant energy source used for heating and cooking, and its lack of odor could lead to dangerous situations if there were a leak. By adding mercaptan, which has a strong, unpleasant odor reminiscent of rotten eggs, it becomes easier for individuals to detect even small amounts of leaking gas. While propane, butane, and methane can also be used as fuels, the characteristic of being odorless before the addition of mercaptan primarily describes natural gas. Propane and butane, though they can be odorless, are often delivered in consumer-ready forms where mercaptan is included. Methane, while a component of natural gas, is not typically referenced separately when discussing odorlessness in this context. Thus, recognizing that natural gas is treated with mercaptan for safety underlines its role in safe residential and commercial energy use.