Across
1
Substance with pH below 7
4
Tissue that contracts for movement
5
Gas essential for breathing
9
Curved glass that refracts light
10
Gas form of a liquid
11
Tectonic landmass section
Down
2
Disturbance that transfers energy
3
Mass per unit volume
6
Basic unit of life
7
Particle of light
8
Icy body with a tail near the sun