Across
1
Amplified beam of light
3
Unit of heredity
4
Unit of force
6
Fourth state of matter
9
Mass per unit volume
10
Blocking of light by a celestial body
Down
2
Group of similar cells
5
Center of an atom or cell
7
Particle of light
8
Molten rock beneath Earth surface
11
Infectious microscopic agent
12
Positive particle in nucleus
13
Compound containing oxygen