Balsa wood is classified as a hard wood!
41
Nylon is made from coal and petroleum.
42
Marie Curie, the Nobel prize winning scientist who discovered radium, died of radiation poisoning.
57
A coal power station puts 100 times more radiation into the air than a nuclear power plant producing the same amount of energy.
7
Optical illusions occur when what the eyes see conflicts with what the brain expects.
75
The brain case [of Neanderthals] on the average was more than 13 percent larger than that of the average of modern man
61
Because heat expands the metal, the Eiffel Tower always leans away from the sun.
79
It takes a photon 170,000 years to travel from the core of the Sun to the surface, but only 8 minutes to travel the rest of the way to Earth.
6