 What best describes how the overall tone changed from the beginning of the article?
But, from what I hear, there are plenty of rock formations. It could start cavities. In fact, anything having to do with atomic science excited him. You couldn’t have a father who was head of the atomic-science department at Oceanview College without picking up a little knowledge along the way. Eddie knew that a radioisotope was a material which had been “cooked” in an atomic reactor until it was “hot” with radioactivity. When carefully controlled, the radiation stored up in such isotopes was used in many beneficial ways. One reason for asking that particular question was to keep from prying deeper into the subject of the radioisotope. At the speed atomic science is moving today, we simply can’t afford to waste time.
 From lighthearted to tense.
 From worrisome to frustrated.  From apathetic to solemn.  From lighthearted to tense.  From upbeat to sympathetic.