How many times should you rinse a pipet before transferring liquid? 2- once with tap water and once with deionized water?

You need to rinse a few times with clean water to dilute and rinse out whatever was in there previously. Then rinse with the solution to be pipetted to rinse out the water and to ensure the solution sits level in the pipette.

Answer ozone (o3) is made of three atoms of oxygen, it is a molecule;