Across
1
Substance with pH below 7
3
Icy body with a tail near the sun
5
Curved glass that refracts light
6
Basic unit of life
7
Reddish electrical conductor
9
Group of similar cells
11
Molten rock beneath Earth surface
Down
2
Naturally occurring inorganic solid
4
Mass per unit volume
6
Element found in all living things
8
Disturbance that transfers energy
10
Unit of energy