Across
1
Biological catalyst
3
Preserved remains of ancient life
5
Positive particle in nucleus
7
Second lightest element
11
Compound containing oxygen
Down
2
Reddish electrical conductor
4
Mass per unit volume
5
Fourth state of matter
6
Absolute temperature scale unit
8
Naturally occurring inorganic solid
9
Smallest unit of an element
10
Substance with pH below 7