Until the early 1960s the group 8A elements were called the inert gases; before that they were

Question:

Until the early 1960s the group 8A elements were called the inert gases; before that they were called the rare gases. The term rare gases were dropped after it was discovered that argon accounts for roughly 1% of Earth's atmosphere.
(a) Why was the term inert gases dropped?
(b) What discovery triggered this change in name?
(c) What name is applied to the group now?