Part II. Multiple choice, continued (3 points each). Name:__________________ Please circle your answer. There is only one correct answer to each question. 5. Which of the following molecular formulas is also an empirical formula? A) C6H6O2 B) C2H6SO C) H2O2 D) C6H6 6. What is the coefficient of O2 when the following equation is completed and balanced? C4H8O2 + O2 à ______________ A) 2 B) 3 C) 5 D) 6 7. Analysis of a compound shows that it contains 3.75 moles of C, 7.50 moles of H, and 1.25 moles of N. What is its empirical formula? A) CHN B) C3H6N C) C4H8N D) C5H9N2 8. What is the molar mass of Ca(NO3)2? (AW Ca = 40.1 amu; N = 14.0 amu; O = 16.0 amu) A) 70.1 g/mol B) 62.0 g/mol C) 164.1 g/mol D) 102.1 g/mol 9. Which of the following is an alkali metal? A) Mg B) Fe C) Al D) Na 10. A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular formula of this compound is A) C2H4O2 B) CH2O C) C2H3O4 D) C2H2O4 11. How many molecules of water, H2O, are there in 28.0 grams of water? A) 9.37 x 1023 B) 1.56 C) 578 D) 1.56 x 1025 12. When a hydrocarbon burns in air, what component of air reacts? A) nitrogen B) oxygen C) carbon dioxide D) water 13. When the following equation is balanced, the coefficient of Fe3O4 is__________. Al + Fe3O4 à Al2O3 + Fe A) 1 B) 2 C) 3 D) 4
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