Question 1

Which of the following best illustrates the Law of Conservation of Mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products in a closed system.

Question 2

A student measures the mass of a sample three times and gets values of 5.12 g, 5.13 g, and 5.11 g. The true value is 5.50 g. Which statement best describes the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is an example of a physical change?

Accepted Answer

Boiling water to produce steam.

Question 4

Which of the following best describes an element?

Accepted Answer

A substance that cannot be broken down into simpler substances by chemical means.

Question 5

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 6

Which of the following is a balanced chemical equation for the combustion of methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 7

A solution contains 0.5 mol of NaCl dissolved in 250 mL of water. What is the molarity of the solution?

Accepted Answer

$$2.0\ \mathrm{M}$$

Question 8

Which of the following statements about oxidation-reduction (redox) reactions is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 9

Which of the following best explains why sodium chloride ($$\mathrm{NaCl}) $$conducts electricity when dissolved in water but not in solid form?

Accepted Answer

In aqueous solution, $$\mathrm{Na^+}$$ and $$\mathrm{Cl^-}$$ ions are free to move and carry charge.

Question 10

A sample of gas occupies 4.0 L at 1.0 atm and 300 K. What volume will it occupy at 2.0 atm and 300 K?

Accepted Answer

$$2.0\ \mathrm{L}$$

Question 11

Which of the following best describes the shape of a water molecule ($$\mathrm{H_2O}$$)?

Accepted Answer

Bent due to two lone pairs on the oxygen atom.

Question 12

Which of the following is the correct electron configuration for a neutral oxygen atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^4$$

Question 13

Which of the following statements about acids and bases is correct according to the Bronsted-Lowry definition?

Accepted Answer

An acid is a proton donor and a base is a proton acceptor.

Question 14

Which of the following is the best example of an exothermic reaction?

Accepted Answer

Combustion of gasoline in a car engine.

Question 15

A reaction has a theoretical yield of 10.0 g and an actual yield of 8.0 g. What is the percent yield?

Accepted Answer

$$80\%$$

Question 16

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water due to its open hydrogen-bonded structure.

Question 17

Which of the following is the correct formula for calculating molarity ($$M$$)?

Accepted Answer

$$M = \dfrac{	ext{moles of solute}}{	ext{liters of solution}}$$

Question 18

Which of the following is a correct statement about the periodic trends in atomic radius?

Accepted Answer

Atomic radius decreases across a period and increases down a group.

Question 19

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of silver nitrate and sodium chloride?

Accepted Answer

$$\mathrm{Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)}$$

Question 20

A sample of calcium carbonate ($$\mathrm{$$CaCO_3$$}) $$decomposes to produce calcium oxide ($$\mathrm{CaO}) $$and carbon dioxide ($$\mathrm{CO_2$}). If 50.0 g of$$ $$\mathrm{$$CaCO_3$$} ($$molar mass = 100.1 g/mol) is decomposed, how many grams of $$\mathrm{CO_2$} ($$molar mass = 44.0 g/mol) are produced?

Accepted Answer

$$22.0\ \mathrm{g}$$

Comprehensive Study Guide: Introduction to Chemistry Final Exam Topics

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