Across
1
Second lightest element
4
Fourth state of matter
5
Ball of burning gas in space
6
Preserved remains of ancient life
Down
2
Compound containing oxygen
3
Center of an atom or cell
7
Substance with pH above 7
8
Group of similar cells
Second lightest element
Fourth state of matter
Ball of burning gas in space
Preserved remains of ancient life
Compound containing oxygen
Center of an atom or cell
Substance with pH above 7
Group of similar cells