Across
1
Path of a planet around the sun
3
Measure of matter in an object
5
Compound containing oxygen
8
Molten rock beneath Earth surface
9
Ball of burning gas in space
12
Disturbance that transfers energy
Down
2
Preserved remains of ancient life
3
The Red Planet
4
Magnetic metallic element
6
Unit of heredity
7
Fourth state of matter
10
Smallest unit of an element
11
Form of thermal energy