Across
1
Amplified beam of light
3
Mass per unit volume
4
Magnetic metallic element
7
Tissue that contracts for movement
10
Unit of energy
12
Measure of matter in an object
13
Natural satellite of Earth
Down
2
Gas essential for breathing
5
Blocking of light by a celestial body
6
Element found in all living things
8
Nerve cell in the brain
9
Biological catalyst
11
Substance with pH below 7
14
Fourth state of matter
15
Gas form of a liquid