Across
1
Icy body with a tail near the sun
4
Unit of power
5
Chemical element in table salt
9
Molten rock beneath Earth surface
10
Unit of electric potential
11
Smallest unit of an element
Down
2
Substance with pH above 7
3
Compound containing oxygen
6
Measure of matter in an object
7
The Red Planet
8
Path of a planet around the sun
9
Tissue that contracts for movement
12
Gas essential for breathing