Across
1
Basic unit of life
4
Push or pull on an object
5
Gas essential for breathing
7
Second lightest element
Down
2
Substance with pH above 7
3
Curved glass that refracts light
4
Preserved remains of ancient life
6
Smallest unit of an element
8
Group of similar cells
9
Icy body with a tail near the sun
10
Glass that splits light into spectrum