Across
1
Path of a planet around the sun
3
Preserved remains of ancient life
4
Naturally occurring inorganic solid
5
Fourth state of matter
8
Second lightest element
9
Push or pull on an object
11
Mass per unit volume
Down
1
Compound containing oxygen
2
Substance with pH below 7
6
Substance with pH above 7
7
Chemical element in table salt
10
Icy body with a tail near the sun
12
Reddish electrical conductor