Across
1
Second lightest element
4
Push or pull on an object
6
Curved glass that refracts light
7
Basic unit of life
10
Unit of power
11
Substance with pH above 7
Down
2
Hottest planet in solar system
3
Blocking of light by a celestial body
5
Biological catalyst
8
Ball of burning gas in space
9
Tissue that contracts for movement
12
Unit of electric potential