1. which of the following statements is not true about double-replacement reactions? a. the product may precipitate from solution. b. the product may be a gas. c. the product may be a molecular compound. d. the reactant may be a solid metal. 2. the complete combustion of which of the following substances produces carbon dioxide and water? a. c8h18 b. k2co3 c. cahco3 d. no 3. the equation mg(s) + 2hcl(aq) + h2(g) is an example of which type of reaction? a. combination reaction b. single-replacement reaction c. decomposition reaction d. double-replacement reaction