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.
For instance, the UN, with its data, considered 1999 October 12 to be the day of six billion, but the approximation here (which I for one have more faith in) puts it at 1999 June 18 or 19 (depending on what time zone you're in), nearly four months earlier.