Across
1
Mass per unit volume
2
Nerve cell in the brain
4
Measure of matter in an object
7
Ball of burning gas in space
9
Substance with pH above 7
Down
2
Center of an atom or cell
3
Tissue that contracts for movement
5
Smallest unit of an element
6
Gas form of a liquid
8
Blocking of light by a celestial body
10
Gas essential for breathing
11
Reddish electrical conductor