Magnesium burns in air with a dazzling brilliance

1. Indicate which of the following is always the same for neutral isotopes of the same element? [You

must select all correct answers.]

A) Atomic number B) Mass number C) Number of neutrons D) Number of protons E) Number of electrons

2. Calculate the relative atomic mass of Morgelium, a fictional element, if it exists in two isotopes with the following abundance and masses:

A) 57.4 amu M #$ 55.90 𝑎𝑚𝑢 70.0% B) 55.3 amu M #. 53.90 𝑎𝑚𝑢 30.0% C) 54.9 amu D) 54.4 amu E) 52.3 amu

3. There are ____ protons, ____ neutrons, and ____ electrons in Rb-87.

A) 37, 50, 37 B) 37, 87, 37 C) 87, 50, 50 D) 87, 37, 50 E) 50, 37, 50

4. The density of liquid carbon tetrachloride is 1.59 g/cm3. What is the mass of a sample of CCl4 that has a volume of 3.0 mL?

A) 43 g B) 4.8 g C) 19 g D) 1.9 g E) 0.53 g

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5. When elements in the alkaline earth group form monatomic ions, what is the charge on each ion?

A) 3- B) 2- C) 1- D) 2+ E) 1+

6. Which of the following elements occurs naturally as diatomic molecules when it is in elemental

form near ambient conditions. [You must select all correct answers.]

A) Neon B) Nitrogen C) Fluorine D) Sulfur E) Sodium

7. What is the empirical formula for iron(III) sulfide?

A) FeS B) Fe3S C) FeS2 D) Fe2S3 E) Fe3S2

8. When the following equation is balanced, the coefficients are ________.

A) NH3 (g) + O2 (g) → NO2 (g) + H2O (g)

A) 1, 1, 1, 1 B) 4, 7, 4, 6 C) 2, 3, 2, 3 D) 1, 3, 1, 2 E) 4, 3, 4, 3

9. A 0.16 M sodium chloride solution is normally used for intravenous injections. Calculate the mass

of salt needed to prepare 250 mL of a solution of this type.

A) 37 g B) 91 g C) 9.1 g D) 2.3 g E) None of the above

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10. Calculate the number of chlorine atoms in 75.0 g of CCl3F.

A) 3.29 x 1023 B) 9.86 x 1023 C) 1.64 x 1024 D) 6.80 x 1023 E) None of the above

11. Which of the following compounds has the smallest mass percent chlorine?

A) BeCl2 B) MgCl2 C) CaCl2 D) SrCl2 E) BaCl2

12. Ascorbic acid contains 40.92% C, 4.58% H and 54.50% O by mass. What is the empirical formula of

ascorbic acid?

A) C2H4O B) C4H3O4 C) C3H4O D) C3H3O E) C3H4O3

13. Solid lithium hydroxide is used in space vehicles to remove the carbon dioxide exhaled by astronauts. The hydroxide reacts with the carbon dioxide to form solid lithium carbonate and liquid water. How many grams of carbon dioxide can be absorbed by 1.00 g of lithium hydroxide?

A) 1.89 g B) 0.919 g C) 1.84 g D) 3.67 g E) 0.500 g

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14. Consider the complete combustion of octane, C8H18. How many grams of O2 are needed to burn

1.50 mol of octane?

A) 800 g B) 267 g C) 400 g D) 384 g E) 600 g

15. Magnesium metal burns in air with a dazzling brilliance to produce magnesium oxide. When 5.50 g of Mg burns, what is the theoretical yield of magnesium oxide?

A) 5.50g B) 9.12 g C) 0.226 g D) 4.56 g E) 18.2 g

16. Mercury(II) oxide decomposes upon heating to mercury metal and oxygen gas. Upon heating a sample of HgO the reaction container and its contents decreased in mass by 0.250 g. What mass of HgO reacted?

A) 0.845 g B) 0.250 g C) 0.500 g D) 1.69 g E) 3.38 g

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17. When a mixture of 10.0 g of acetylene (C2H2) and 10.0 g of oxygen (O2) is ignited, the resulting combustion reaction produces CO2 and H2O. Assuming the reaction goes to completion, how many grams of C2H2 are present after the reaction?

A) 6.75 g B) 3.26 g C) 5.93 g D) 4.07 g E) 0.00 g

18. A sample of 0.30 mol of potassium phosphate is added to 20.0 mL of 0.15 M silver nitrate, resulting

in the formation of a precipitate. Calculate the theoretical yield, in moles, of the precipitate that forms.

A) 0.0010 mol B) 0.0020 mol C) 0.0030 mol D) 0.0060 mol E) 0.0090 mol

19. You are presented with a white solid and told that due to careless labeling it is not clear if the

substance is barium chloride, lead chloride, or zinc chloride. When you transfer the solid to a beaker and add water, the solid dissolves to give a clear solution. Next, a Na2SO4 (aq) solution is added and a white precipitate forms. What is the identity of the unknown white solid?

A) BaCl2 B) PbCl2 C) ZnCl2 D) PbCl E) BaCl

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20. EXTRA CREDIT. Which of the following metals will react in acid solutions to form H2 gas? [You must select all correct answers.]

A) Mg B) Al C) Fe D) Cu E) Ag

21. EXTRA CREDIT. Which of the following metals will be oxidized by Zn(NO3)2? [You must select all correct answers.]

A) Mg B) Al C) Fe D) Cu E) Ag

22. EXTRA CREDIT. What is the oxidation number of sulfur in Na2SO4

A) -2 B) 0 C) +2 D) +4 E) +6

23. The total concentration of ions in a 0.250 M solution of HCl is A) 0 B) 0.125 M C) 0.250 M D) 0.500 M E) 0.750 M

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24. If 65 ml of a 0.430 M NaOH solution is diluted to 500 mL, what is the concentration of the diluted solution?

A) 0.215 M B) 0.30 M C) 0.023 M D) 3.3 M E) 0.056 M

25. The net ionic equation for the reaction between aqueous nitric acid and aqueous sodium hydroxide is

A) H + (aq) + HNO3 (aq) + 2OH

- (aq) → 2H2O (l) + NO3 - (aq)

B) HNO3 (aq) + NaOH (aq) → NaNO3 (aq) + H2O (l) C) H+(aq) + OH- (aq) → H2O(l) D) HNO3 (aq) + OH

- (aq) → NO3 - (aq) + H2O (l)

E) H+ (aq) + Na+ (aq) + OH- (aq) → H2O (l) + Na + (aq)