题目

William lived with his parents and seven sisters in a small clay house without electricity or running water. Like most boys in his village, William was expected to assist his parents on the family farm, as well as keep up with his school work. However, in 2003 at the age of 13, William and many other children were forced to drop out of school when their parents could no longer afford his schooling. William had to work even harder to help his family, but he wasn’t ready to give up his education. He went to the local library and took out some books to study. One book, called Using Ene味精是烹饪中不可缺少的调味品，其主要成分为谷氨酸钠（化学式为C5H8NO4Na），著名的“莲花”牌味精，其谷氨酸钠的含量可达85%以上，请回答：（1）谷氨酸钠的相对分子质量为169169；（2）一袋包装为50克的“莲花”牌味精中，谷氨酸钠的质量不少于42.542.5克．