5. Determine the empirical formula for a compound that contains C, H and O. It contains 51.59% C and 35.30% O by mass. (C: 12.0 g/mol； H: 1.00 g/mol； O:6.0 g/mol)
(A) C₂H₆O
(B) CHO
(C)
(D) CH₄O₃

1. A student performs an experiment to determine the density of a sugar solution. She obtains the following results: 4.71 g/mL, 4.73 g/mL, 4.67 g/mL, 4.69 g/mL. If the actual value for the density of the sugar solution is 4.40 g/mL, which statement below best describes her results? (A) Her results are precise, but not accurate. (B) Her results are accurate, but not precise. (C) Her results are both precise and accurate. (D) Her results are neither precise nor accurate.

2. What answer should be reported, with the correct number of significant figures, for the following calculation? (249.362 + 41) / 63.498 (A) 4.6 (B) 4.57 (C) 4.573 (D) 4.5728

3. Write the name for Ca3(PO4)2. (A) calcium (III) phosphite (B) calcium (II) phosphite (C) calcium phosphate (D) tricalcium phosphorustetraoxide

4. Give the correct formula for aluminum sulfate. (A) Al2SO4 (B) Al(SO4)3 (C) Al3(SO4)2 (D) Al2(SO4)3

6. Give the theoretical yield, in grams, of CO2 from the reaction of 4.000 moles of with 4.000 moles of O2. (C: 12.0 g/mol； H: 1.00 g/mol； O: 16.0 g/mol) (A)112.7 g (B)102.4 g (C)176.0 g (D)704.0 g

7. The titration of 25.0 mL of an unknown concentration H2SO4 solution requires 83.6 mL of 0.12 M LiOH solution. What is the concentration of the H2SO4 solution (in M)? (A) 0.20 M (B) 0.40 M (C) 0.10 M (D) 0.36 M

8. How many subshells are there in the shell with n = 4? (A) 3 (B) 4 (C) 6 (D) 18

9. How many valence electrons does an atom of C have? (A) 1 (B) 4 (C) 2 (D) 3

10. Place the following in order of increasing radius. Ca2⁺   S2⁻   Cl⁻ (A)(B) (C) (D)

11. Which of the elements listed below would most likely form a polar covalent bond when bonded to oxygen? (A) Mg (B) H (C) Al (D) O