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.
WHO marks 20th Anniversary of World Mental Health Day. 9 October 2012 | GENEVA - On World Mental Health Day (10 October), WHO is calling for an end to the stigmatization of depression and other mental disorders and for better access to treatment for all people who need it.