Important Chemistry Questions

I have a list of chemistry questions that I think everyone should be able to answer. Is there a chemistry question you think a person with a command of chemistry should be able to answer? It could be a question that's so important, you think people should know the answer or it could be a question that someone who passed chemistry ought to be able to answer based on what they should have learned. Here's your chance to educate or to learn. Pose a chemistry question and answer it or view the questions submitted by others. Try it...