Explain why some symbols - for example, Cl and Si - have two letters

Electric charge is what ? a. kinetic energy b. radiation c. discovery d. electricity

Amixture that has two or more substances that are spread out evenly is called a. compound b. heterogeneous c. substance d. homogeneous

Suppose that some of the compound spilled out of the crucible after it was heated. would that cause the percent by mass of water in the compound determined by the experiment to be too low, too high, or unchanged? briefly explain your answer.