- Rubidium is a chemical element; it has symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes: 72% is a stable isotope 85Rb, and 28% is slightly radioactive 87Rb, with a half-life of 48.8 billion years – more than three times as long as the estimated age of the universe.
- Pitfall! (Wikipedia)
Pitfall! is a video game developed by David Crane for the Atari 2600 and released in 1982 by Activision. The player controls Pitfall Harry, who has a time limit of 20 minutes to seek treasure in a jungle. The game world is populated by enemies and hazards that variously cause the player to lose lives or points.