Across
1
Mass per unit volume
5
Nerve cell in the brain
6
Measure of matter in an object
8
Center of an atom or cell
12
Unit of power
Down
2
Precious yellow metallic element
3
Icy body with a tail near the sun
4
Tissue that contracts for movement
7
Our home planet
9
Absolute temperature scale unit
10
Glass that splits light into spectrum
11
Particle of light