Across
1
Icy body with a tail near the sun
4
Positive particle in nucleus
7
Gas form of a liquid
8
Substance with pH above 7
10
Curved glass that refracts light
11
Substance with pH below 7
12
Ball of burning gas in space
Down
2
Molten rock beneath Earth surface
3
Tissue that contracts for movement
4
Tectonic landmass section
5
Reddish electrical conductor
6
Group of similar cells
9
Natural satellite of Earth