Across
1
Chemical element in table salt
4
Second lightest element
6
Blocking of light by a celestial body
8
Substance with pH above 7
10
Natural satellite of Earth
12
Substance with pH below 7
Down
2
Nerve cell in the brain
3
Hottest planet in solar system
5
Naturally occurring inorganic solid
7
Disturbance that transfers energy
9
Gas essential for breathing
11
Infectious microscopic agent