Across
1
Unit of heredity
4
Precious yellow metallic element
5
Disturbance that transfers energy
6
Substance with pH below 7
9
Center of an atom or cell
10
Curved glass that refracts light
Down
2
Blocking of light by a celestial body
3
Substance with pH above 7
7
Amplified beam of light
8
Mass per unit volume
11
Second lightest element