Across
1
Icy body with a tail near the sun
4
Biological catalyst
7
Fourth state of matter
8
Absolute temperature scale unit
9
Magnetic metallic element
10
Group of similar cells
12
Tissue that contracts for movement
Down
2
Nerve cell in the brain
3
Naturally occurring inorganic solid
5
Hottest planet in solar system
6
Mass per unit volume
11
Second lightest element