Across
1
Disturbance that transfers energy
4
Unit of force
5
Second lightest element
7
Nerve cell in the brain
9
Gas form of a liquid
11
Compound containing oxygen
Down
2
Gas essential for breathing
3
Our home planet
6
Molten rock beneath Earth surface
8
Unit of energy
10
Reddish electrical conductor
12
Hottest planet in solar system
13
Magnetic metallic element