Across
1
Ball of burning gas in space
3
Substance with pH above 7
5
Unit of force
7
Basic unit of life
8
Molten rock beneath Earth surface
10
Unit of heredity
Down
2
Path of a planet around the sun
4
Hottest planet in solar system
6
Substance with pH below 7
7
Icy body with a tail near the sun
9
Gas essential for breathing