Oxygen in the air. The percentage of oxygen in the air can be measured by passing a known volume of air over hot copper, and measuring the decrease in volume as the oxygen reacts with it. Here are the equations for this reaction: copper + oxygen â copper oxide. 2Cu + O2 â 2CuO.
Get ready - World Backup is March 31st! About World Backup Day is a day for people to learn about the increasing role of data in our lives and the importance of regular backups.
World Water Day, held every March 22, is taking place around the world on Wednesday, aiming at attracting attention to the water crisis with this year's theme: Waste Water.. The day was originally launched in 1993 by the U.N. To coincide with the 2017 date, reports have been published warning of severe water scarcity in parts of Africa and Iran.