Question 1

Which law is demonstrated by the balanced chemical equation $$\mathrm{CH_4$ (g) + 2\ O_2$ (g) \rightarrow CO_2$ (g) + 2\ H_2O (g)} as $$shown in the image, where the number of each type of atom is the same on both sides of the equation?

Accepted Answer

Law of Conservation of Mass

Question 2

Given the reaction $$\mathrm{2\ Mg (s) + O_2$ (g) \rightarrow 2\ MgO (s)}$$, what type of reaction is this?

Accepted Answer

Combination (synthesis)

Question 3

Which of the following is the correct net ionic equation for the reaction between aqueous lead(II) nitrate and aqueous potassium iodide?

Accepted Answer

$$\mathrm{Pb$$^{2+}$$ (aq) + 2\ I^- (aq) \rightarrow $$PbI_2$$ (s)}$$

Question 4

A sample of ethane ($$\mathrm{C_2H_6}) $$undergoes complete combustion. What is the balanced equation for this reaction?

Accepted Answer

$$\mathrm{2\ C_2H_6 + 7\ O_2$ \rightarrow 4\ CO_2$ + 6\ H_2O}$$

Question 5

Which of the following compounds is insoluble in water according to the solubility rules?

Accepted Answer

Calcium carbonate ($$\mathrm{$$CaCO_3$$})$$

Question 6

What is the empirical formula of a compound that contains 61.31% C, 5.14% H, 10.21% N, and 23.33% O by mass?

Accepted Answer

$$\mathrm{C_7H_7NO_2}$$

Question 7

A solution is prepared by dissolving 5.25 g of oxalic acid ($$\mathrm{C_2O_4H_2}) in 155 mL of $$water (density = 1.00 g/mL). What is the percent by mass of oxalic acid in the solution?

Accepted Answer

3.28%

Question 8

Which of the following is a redox reaction?

Accepted Answer

$$\mathrm{Zn (s) + 2\ HCl (aq) \rightarrow $$ZnCl_2$$ (aq) + H_2$ (g)}$$

Question 9

What is the oxidation number of sulfur in $$\mathrm{H_2SO_4}$$?

Accepted Answer

+6

Question 10

If 28.6 kg of C reacts with 88.2 kg of $$\mathrm{$$TiO_2$$} to $$produce 42.8 kg of Ti, what is the percent yield of Ti? (Molar masses: C = 12.01 g/mol, TiO$$_2 = 79.87 g/$$mol, Ti = 47.87 g/mol)

Accepted Answer

80.9%

Question 11

Which of the following is the correct molecular formula for a compound with an empirical formula of $$\mathrm{CH_2O}$$ and a molar mass of 180 g/mol?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$}$$

Question 12

Which of the following is the limiting reactant when 0.20 mol of boron reacts with 0.10 mol of chlorine gas to form $$\mathrm{B_2Cl_4}$$?

Accepted Answer

Chlorine gas ($$\mathrm{Cl_2$})$$

Question 13

What is the net ionic equation for the neutralization reaction between hydrochloric acid and sodium hydroxide?

Accepted Answer

$$\mathrm{H^+ (aq) + OH^- (aq) \rightarrow H_2O (l)}$$

Question 14

How many molecules are present in 0.032 g of water ($$\mathrm{H_2O}$$)? (Molar mass of $$\mathrm{H_2O} = 18.02 g/$$mol, Avogadro's number = $$6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.07 	imes 10$$^{21}$$

Question 15

Which of the following is a strong acid?

Accepted Answer

Hydrochloric acid ($$\mathrm{HCl})$$

Question 16

What is the molarity of a solution prepared by dissolving 10.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 500 mL of solution?

Accepted Answer

0.342 M

Question 17

Which of the following best describes the role of a limiting reactant in a chemical reaction?

Accepted Answer

It determines the maximum amount of product that can be formed.

Question 18

What is the percent composition by mass of carbon in ethane ($$\mathrm{C_2H_6}$$)? (Atomic masses: C = 12.01, H = 1.008)

Accepted Answer

80.00%

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