A US ton is equivalent to 900 kg (2000 pounds). A British ton is 1008 kg (2240 pounds), called a gross ton.

Hydrogen gas is the least dense substance in the world.

The double-helix structure of DNA was discovered in 1953 by James Watson and Francis Crick. The length of a single human DNA molecule, when extended, is 1.7 metres (5 ft 5 in).

A square piece of dry paper cannot be folded in half more than 7 times.

Since space is essentially empty it cannot carry sound. Therefor there is no sound in space, at least not the sort of sound that we are used to.