Question

Which noble gas makes up about 1 percent of Earth's atmosphere?

Answer 1

Argon is the third most abundant gas in our atmosphere, making up about one percent in terms of moles of gas.

Explanation:

Roughly, our atmosphere is 78% nitrogen, 21% oxygen, 1% argon, and trace amounts of many other gases plus variable amounts of water vapor. See http://www.universetoday.com/26656/composition-of-the-earths-atmosphere/.