Across
1
Chemical element in table salt
4
Ball of burning gas in space
6
Substance with pH above 7
7
Positive particle in nucleus
10
Unit of electric potential
12
Biological catalyst
Down
2
Center of an atom or cell
3
Icy body with a tail near the sun
5
Preserved remains of ancient life
7
Particle of light
8
Unit of power
9
Form of thermal energy
11
Our home planet
13
Gas essential for breathing
14
Natural satellite of Earth