Across
1
Disturbance that transfers energy
3
Hottest planet in solar system
5
Gas essential for breathing
7
Infectious microscopic agent
8
Reddish electrical conductor
11
Second lightest element
Down
2
Biological catalyst
4
Tissue that contracts for movement
6
Ball of burning gas in space
9
Blocking of light by a celestial body
10
Unit of energy
12
Basic unit of life