Across
1
Gas essential for breathing
4
Chemical element in table salt
6
Form of thermal energy
7
Reddish electrical conductor
9
Substance with pH above 7
10
Path of a planet around the sun
13
Positive particle in nucleus
Down
2
Tectonic landmass section
3
Nerve cell in the brain
5
Icy body with a tail near the sun
8
Group of similar cells
11
Hottest planet in solar system
12
Unit of force