Answer
Oxygen is not a noble gas discovered by Ramsay. Noble gases are a group of elements that are all gases at room temperature and have very low reactivity. They include helium, neon, argon, krypton, xenon, and radon. Ramsay discovered three of these gases: argon, krypton, and xenon. Oxygen, on the other hand, is a reactive gas that is not a noble gas. It was discovered by Joseph Priestley in 1774.