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. 22 March 2017. World Water Day is held annually on 22 March as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources. An international day to celebrate freshwater was recommended at the 1992 United Nations Conference on Environment and Development (UNCED).