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.
The United Nations' (UN) World Population Day is annually observed on July 11 to reaffirm the human right to plan for a family.he United Nations' (UN) World Population Day is annually observed on July 11 to reaffirm the human right to plan for a family.