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.
World Thinking Day. As a Girl Scout, you are part of a special network of girls that stretches across the world. On February 22 of each year, Girl Scouts and Girl Guides from 146 countries celebrate World Thinking Day (WTD). (Thatâs one big celebration!) Every year, World Thinking Day is a great opportunity to rally your global sisterhood around a particular theme. The World Thinking Day 2016 theme is âConnect.â. This World Thinking Day, Girl Scouts and Girl Guides will explore and celebrate the connections that make life happier.