Across
1
Biological catalyst
4
Path of a planet around the sun
6
Curved glass that refracts light
7
Smallest unit of an element
8
Icy body with a tail near the sun
Down
2
Molten rock beneath Earth surface
3
Tectonic landmass section
4
Compound containing oxygen
5
Mass per unit volume
9
Ball of burning gas in space
10
Form of thermal energy
11
Gas form of a liquid