Usually the sprocket is an inseparable part of the freewheel, and the size of the freewheel is determined by the hub.

Freewheel Burning was created in 1983-09.

On the front it's usually called a chainwheel or a chainring, on the rear it's either a sprocket, a cassette, or a freewheel.

FreeWheel - 2011 was released on:

USA: 2011

Depends on if it's a freewheel or a freehub design. For a freewheel you need the appropriate freewheel puller. For a freehub you need a splined lockring tool.