Name CHE 131, Test 1September 26, 2001Multiple choice. (2 points each)1. Classify the following reaction2 K (s)+ Br2 (l) 2 KBr (s)(a) precipitation reaction(b) acid base reaction (neutralization)(c) oxidation-reduction reaction(d) none of the above2. The average mass of a carbon atom is 12.011. Assuming you were able to pick up only one carbon unit, the chances that you would randomly get one with a mass of 12.011 is (a) 0% (b) 0.011% (c) about 12% (d) 12.011% (e) greater than 50%3. 24020Ca has(a) 20 protons, 20 neutrons, and 18 electrons.(b) 22 protons, 20 neutrons, and 20 electrons.(c) 20 protons, 22 neutrons, and 18 electrons.(d) 22 protons, 18 neutrons, and 18 electrons.(e) 20 protons, 20 neutrons, and 22 electrons.4. According to the law of definite proportions:(a) if the same two elements form two different compounds, they do so in the same ratio.(b) it is not possible for the same two elements to form more than one compound.(c) the ratio of the masses of the elements in a compound is always the same.(d) the total mass after a chemical change is the same as before the change.5. A set of tested hypotheses that gives an overall explanation of some natural phenomenon is called a(n)(a) observation.(b) measurement.(c) theory.(d) natural law.(e) experiment.Short answer:6. Predict the products formed in each of the following reactions, indicating which will be a solid. Give a net ionic equation for each reaction. (7 points for each reaction)K2S (aq)+ Ni(NO3)2 (aq)BaCl2 (aq)+ KCl (aq)7. Briefly describe J.J. Thomson’s cathode ray tube and explain the significance of his observations. (10 points)8. Briefly explain how fluoride helps to prevent tooth decay. (8 points)Problems. Show your work and use the correct number of significant figures for full credit.9. Calcium hydroxide (0.0200 M) is reacted with 35.00 mL of 0.0500 M nitric acid (HNO3). (15 points)(a) Write a balanced chemical equation corresponding to this reaction.(b) Classify the type of reaction as acid-base, precipitation, or oxidation-reduction.(c) What volume of calcium hydroxide is needed to react completely with the nitric acid?10. Methane (CH4) is the main component of marsh gas. Heating methane in the presence of sulfur produces carbon disulfide and hydrogen sulfide, according to the reaction shown below. (15 points)CH4+ S8 H2S + CS2(a) Balance the chemical reaction.(b) Classify the type of reaction as acid-base, precipitation, or oxidation-reduction.(c) What is the theoretical yield for this reaction if it is carried out with 156 g of CH4 and 124 g of S8?(d) What is the percent yield for the formation of carbon disulfide in this reaction, given that 87 g of CS2 are formed?11. Adipic acid is an organic compound composed of 49.31% C, 43.79%H, and the rest hydrogen. If the molar mass of adipic acid is 146.1 g/mol, what are the empirical and molecular formulas for adipic acid? (10 points)Essay. Write your answer in complete sentences, using proper grammar. Please continue your answer on the back of this sheet. (18 points)12. The development of Dalton’s atomic theory was a significant step in the advancement of chemistry as a science. List the postulates of Dalton’s theory. Describe how Dalton’s theory explains the laws of definite proportions (constant composition) and multiple proportions. Which postulates of Dalton’s theory have been discarded in favor of the current atomic theory?