I have a Science fair project. This is the

Question

Science Fair Quetsion: Which brand of soda retains its gas the longest?

My Problem is that I don't know how to measure gas. Can some one who knows please help me.

open the bottles of soda at the same time and check every few minutes to see which one has bubbles the longest.

explain how matter is transferred from one organism to another and between organisms and their enviroment?