Across
1
Gas essential for breathing
4
Fourth state of matter
6
Path of a planet around the sun
7
Biological catalyst
8
Natural satellite of Earth
12
Preserved remains of ancient life
13
Smallest unit of an element
Down
2
Magnetic metallic element
3
Amplified beam of light
5
Curved glass that refracts light
9
Hottest planet in solar system
10
Measure of matter in an object
11
The Red Planet