Q. Which of the following form gaseous fuels at room temperature?

1. Methane
2. Ethane
3. Propane
4. Butane

Select the correct answer using the codes given below:
Answer: 1, 2 & 3
Notes: At room temperature and atmospheric pressure, methane, ethane, and propane exist as gases. Butane, however, exists as a liquefied gas under slight pressure, as found in LPG. Thus, only methane, ethane, and propane are gaseous fuels at room temperature, while butane is not.