Question 1

Which of the following compounds is already in its empirical formula?

Accepted Answer

$\mathrm{MgCl}_2$

Question 2

Which of the following elements does NOT exist as a diatomic molecule in nature?

Accepted Answer

Helium

Question 3

What is the mass of 0.500 moles of chlorine gas ($\mathrm{Cl}_2$)?

Accepted Answer

$35.7\ \mathrm{g}$

Question 4

Which of the following compounds forms an electrolyte solution when dissolved in water?

Accepted Answer

$\mathrm{NaCl}$ (sodium chloride)

Question 5

A precipitate is expected to be formed when an aqueous solution of sodium sulfate is added to an aqueous solution of:

Accepted Answer

Barium chloride

Question 6

How many moles are there in 12.5 grams of iron ($\mathrm{Fe}$)? ($\mathrm{M_{Fe}} = 55.85\ \mathrm{g/mol}$)

Accepted Answer

$0.224\ \mathrm{mol}$

Question 7

Which of the following is the correct molecular formula for potassium nitrate?

Accepted Answer

$\mathrm{KNO}_3$

Question 8

Which of the following is NOT a sign that a chemical reaction has occurred?

Accepted Answer

Evaporation of water

Question 9

What is the percent composition of carbon in oxalic acid ($\mathrm{C}_2\mathrm{H}_2\mathrm{O}_4$)?

Accepted Answer

$26.7\%$

Question 10

Which of the following reactions is a double displacement reaction?

Accepted Answer

$\mathrm{BaCl}_2 + \mathrm{Na}_2\mathrm{SO}_4 \rightarrow \mathrm{BaSO}_4 + 2\mathrm{NaCl}$

Question 11

What is the molarity of a solution prepared by dissolving 43.7 g of NaCl in a total volume of 335 mL of water? ($\mathrm{M_{NaCl}} = 58.44\ \mathrm{g/mol}$)

Accepted Answer

$1.34\ \mathrm{M}$

Question 12

Which of the following is the best procedure to prepare 2.00 L of 1.00 M Na$_2$CO$_3$ solution?

Accepted Answer

Weigh 212 g Na$_2$CO$_3$ and add water until the total solution volume is 2.00 L

Question 13

Which of the following would NOT be present in the net ionic equation for the precipitation reaction: $\mathrm{Pb(NO}_3)_2 + 2\mathrm{KI} \rightarrow \mathrm{PbI}_2 + 2\mathrm{KNO}_3$?

Accepted Answer

$\mathrm{K}^+$

Question 14

Which of the following is a molecular acid?

Accepted Answer

$\mathrm{H}_2\mathrm{SO}_4$

Question 15

How many molecules of sulfur trioxide are in 78.0 grams? ($\mathrm{M_{SO_3}} = 80.07\ \mathrm{g/mol}$)

Accepted Answer

$5.87 	imes 10^{23}$

Question 16

Which of the following is the oxidizing agent in the reaction: $2\mathrm{Na} + 2\mathrm{H}_2\mathrm{O} \rightarrow 2\mathrm{NaOH} + \mathrm{H}_2$?

Accepted Answer

$\mathrm{H}_2\mathrm{O}$

Question 17

Which of the following is a sign that a chemical reaction has occurred when a solution is heated and bubbles form?

Accepted Answer

Formation of a gas

Question 18

What is the molecular formula for chrysotile if its empirical formula is $\mathrm{Mg}_3\mathrm{Si}_2\mathrm{H}_4\mathrm{O}_9$ and its molar mass is 520.0 g/mol? (Empirical mass = 260.1 g/mol)

Accepted Answer

$\mathrm{Mg}_6\mathrm{Si}_4\mathrm{H}_8\mathrm{O}_{18}$

Question 19

Which of the following is the best description of a spectator ion in a chemical reaction?

Accepted Answer

An ion that is unchanged on both sides of the equation

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