What is always true of a combustion reaction? (2 points) a.) water will always be one of the products b.) the reaction releases a large amount of energy c.) one reactant must contain hydrogen d.) carbon dioxide is one of the reactants

Which substances have the lowest melting points: ionic covalent, or metallic

What is the atomic number of an atom that has 6 protons

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