Across
1
Mass per unit volume
5
Push or pull on an object
6
Curved glass that refracts light
7
Fourth state of matter
9
Gas form of a liquid
10
Unit of energy
11
Group of similar cells
12
Substance with pH below 7
13
Disturbance that transfers energy
Down
2
Biological catalyst
3
Naturally occurring inorganic solid
4
Particle of light
5
Preserved remains of ancient life
8
Tissue that contracts for movement