Which of the following gas is NOT a noble gas?

Helium Argon Radon Methane

Methane

The correct answer is option 4. Methane. The noble gases are helium, argon, krypton, xenon, and radon, in order of their mass. They are called noble gases because they are so majestic that they do not react with anything in general. They're also known as inert gases for this reason.