Sound travels about 4 times faster in water than in air.
408
Scientists are learning from the 1700-year-old Lycurgus Cup, which changes colour thanks to nano particles.
0
Iron weighs more after it rusts.
16
Because heat expands the metal, the Eiffel Tower always leans away from the sun.
79
The only letter not appearing on the Periodic Table is the letter "J".
180
The most expensive material on the planet is antimatter - worth $62.5 trillion per gram.
18
Optical illusions occur when what the eyes see conflicts with what the brain expects.
75