Question

1) In a chemical reaction, if a color change is detected, if an odor change is detected, or if a precipitate is formed, then:
A. a chemical reaction has definitely occurred
B. only physical reactions have occurred
C. a chemical reaction may have occurred
D. both physical and chemical reactions have definitely occurred

2) If different products are not created during a process, then a chemical reaction has not occurred.
A. True
B. False

Answer 1

3) Chemical equations provide:
A. the physical state of each reactant and product
B. the ratios of reactants and products
C. the chemical identity of the reactants and products
D. all of the above information

4) When written in a chemical equation, the symbols (s), (g), () and (aq), indicate whether the reaction will proceed quickly or more slowly.
A. True
B. False

5) From the balanced chemical equations listed below, which equation best expresses the following word equation: Hydrogen gas plus oxygen gas yields water vapor plus energy?

A. 2H2O (g) ---> 2H2 (g) + O2 (g) + energy

B. 2H + O ---> 2HO + energy

C. 2H2 (g) + O2 (g) ---> 2H2O (g) + energy

D. 2H2 (g) + O2 (g) + energy ---> 2H2O (l)

6) The balanced chemical equation, 2NO (g) + 5H2 (g) ---> 2NH3 (g) + 2H2O (g), can be expressed in words as:

A. Nitrogen dioxide gas plus hydrogen gas yields ammonia gas plus water
B. Nitrogen monoxide gas plus hydrogen gas yields ammonia gas plus water vapor
C. Nickel monoxide gas plus hydrogen gas yields nitrogen trihydride plus water
D. Nitrogen oxide gas plus hydrogen gas yields ammonia gas plus water vapor