Across
1
Mass per unit volume
3
Curved glass that refracts light
4
Blocking of light by a celestial body
7
Unit of force
8
Substance with pH below 7
Down
2
Hottest planet in solar system
3
Amplified beam of light
5
Unit of heredity
6
Unit of energy
7
Center of an atom or cell
9
Group of similar cells
10
Unit of power