When raymond observes certain natural phenomena, he often forms ideas about their causes and effects. suppose that raymond surmises that leaves change color in autumn due to scarcity of sunlight. in order to test whether his idea is accurate, he must first construct a falsifiable that defines a clear relationship between two variables. raymond's next step is to that would isolate and test the relationship between the two variables. this task can be pretty daunting because raymond will need to identify and eliminate any variables that could confuse test results.

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.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.