Across
1
Biological catalyst
4
Mass per unit volume
5
Curved glass that refracts light
6
Icy body with a tail near the sun
10
Positive particle in nucleus
11
Substance with pH above 7
Down
2
Fourth state of matter
3
Group of similar cells
6
Solid with repeating atomic pattern
7
Naturally occurring inorganic solid
8
Ball of burning gas in space
9
Element found in all living things