1) The smallest unit of time is known as a zeptosecond, which is equal to one trillionth of one billionth of a second.

2) The fall of the Berlin Wall in 1989 symbolized the end of the Cold War and the reunification of East and West Germany.

3) The first video game console, the Magnavox Odyssey, was released in 1972 and featured games such as Pong and Table Tennis.

4) Mountains are formed through various geological processes, including tectonic plate movements, volcanic activity, and erosion.