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 World Health Organization established World AIDS Day in 1988. World AIDS Campaign is the leading international organization which plans and implements the observance. The White House will host a December 1 event at noon to recognize the observance day. Watch the livestream here at noon til 2:00 p.m.