What is the secondmost abundant element in the universe?

1 Answer
Mar 12, 2017

Helium

Explanation:

The most abundant element is hydrogen, making up about #90#%, then helium at about #10#%. All other elements put together are less than #1#%.

The most abundant isotope of helium is #""^4 He#, with a mass about #4# times that of the most common isotope #""^1 H# of hydrogen. In terms of mass, helium makes up about #24#% of the mass of the universe.