Across
1
Compound containing oxygen
4
Push or pull on an object
7
Ball of burning gas in space
8
Substance with pH above 7
11
Unit of power
Down
2
Amplified beam of light
3
Unit of energy
5
Second lightest element
6
Nerve cell in the brain
9
Fourth state of matter
10
The Red Planet
12
Icy body with a tail near the sun