What is an equation of chemical symbols and formulas that record the process of a chemical reaction called? Is there multiple answers?

Can someone me with questions 12 and 13 plz.

What are four significant sources of ghgs that come from wostem washington?

An unknown substance is a white solid at room temperature and has a melting point of 78 °c. which of the following substances is most likely to be the identity of the unknown sample? a. naphthalene, a molecular solid with the formula c10h8 b. silica, a network solid held together by covalent bonds with the formula sio2 c. calcium chloride, an ionic compound with the formula cacl2 d. water, an molecular compound with the formula h2o