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.
Health â 05 September 2013. The World Health Organization (WHO) sponsors the celebration of World Health Day on April 7 every year. the First World Health Assembly held by the WHO in 1948 declared that it would celebrate April 7 as World Health Day to mark the founding the WHO as well as to ensure that health concerns are highlighted too.