Across
1
Tissue that contracts for movement
4
Gas essential for breathing
5
Nerve cell in the brain
7
Positive particle in nucleus
8
Substance with pH above 7
10
Naturally occurring inorganic solid
11
Mass per unit volume
Down
2
Hottest planet in solar system
3
Reddish electrical conductor
4
Compound containing oxygen
6
Unit of force
9
Molten rock beneath Earth surface