Questions

Speed in a given direction is called Velocity.

The process which wherein an Ecosystem may renew itself is known as Ecological Succession.

The time scale may be decades or a million of years after a mass extinction. 

It may be achieve over a period of time.

Intersection method of expressing direction is indicated in the illustration.

A colored ion generally indicates a transition metal.

Friend is a person with whom one has a bond of mutual affection, typically one exclusive of sexual or family relations.

Other names for friend are mate, bosom friend, classmate, buddy, ally,...