Is boiling water a physical or a chemical change? explain why?

It is a physical change. It is a physical change because when you boil water, all you are doing is changing it from a liquid to a gaseous state. When you change the phase of something, it is a physical change, not a chemical one.

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.