Question 1

Which of the following best describes the law of conservation of mass as it applies to a chemical reaction in a closed system?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 2

A sample contains 3.0 moles of NaCl. What is the mass of this sample? (Molar mass of NaCl = $$58.44\ \mathrm{g/mol})$$

Accepted Answer

$$174.0\ \mathrm{g}$$

Question 3

Which of the following statements correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound consists of two or more elements chemically combined in a fixed ratio, while a mixture consists of two or more substances physically combined.

Question 4

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

Accepted Answer

Combustion of gasoline in a car engine

Question 5

A student is asked to write the electron configuration for a neutral atom of phosphorus ($$Z=15). $$Which of the following is correct?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^3$$

Question 6

Which of the following best explains why water ($$\mathrm{H_2O}) is a $$polar molecule?

Accepted Answer

The molecule has a bent shape and a significant difference in electronegativity between hydrogen and oxygen.

Question 7

A solution is prepared by dissolving $$10.0\ \mathrm{g} of $$NaOH in enough water to make $$500.0\ \mathrm{mL} of $$solution. What is the molarity of the solution? (Molar mass of NaOH = $$40.00\ \mathrm{g/mol})$$

Accepted Answer

$$0.50\ \mathrm{M}$$

Question 8

Which of the following is the correct balanced chemical equation for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$\mathrm{C_3H_8} + 5\ \mathrm{O_2$} \rightarrow 3\ \mathrm{CO_2$} + 4\ \mathrm{H_2O}$$

Question 9

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

Accepted Answer

An acid is a substance that donates a proton ($$\mathrm{H^+}$$), and a base is a substance that accepts a proton.

Question 10

A radioactive isotope has a half-life of 3 days. If you start with $$80\ \mathrm{mg}$$, how much remains after 9 days?

Accepted Answer

$$10\ \mathrm{mg}$$

Question 11

Which of the following best describes the difference between a physical and a chemical property?

Accepted Answer

A chemical property describes a substance's ability to undergo changes that transform it into different substances.

Question 12

Which of the following is the correct Lewis structure for carbon dioxide ($$\mathrm{CO_2$}$$)?

Accepted Answer

O=C=O, with each O atom having two lone pairs

Question 13

A sample of gas occupies $$2.0\ \mathrm{L} at$$ $$1.0\ \mathrm{atm}$$ and $$300\ \mathrm{K}. $$What will be its volume at $$2.0\ \mathrm{atm}$$ and $$300\ \mathrm{K}$$, assuming ideal gas behavior?

Accepted Answer

$$1.0\ \mathrm{L}$$

Question 14

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of electrons.

Question 15

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 16

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 17

Which of the following best describes the function of a buffer in a biological system?

Accepted Answer

A buffer resists changes in pH when small amounts of acid or base are added.

Question 18

Which of the following is a correct statement about the Bohr model of the atom?

Accepted Answer

Electrons orbit the nucleus in fixed energy levels.

Question 19

Which of the following is the correct IUPAC name for $$\mathrm{CH_3CH_2CH_2CH_3}$$?

Accepted Answer

Butane

Question 20

Which of the following best describes the process of protein synthesis in cells?

Accepted Answer

DNA is transcribed to mRNA, which is then translated to form a protein.

Introduction to Chemistry: Structured Study Guide and Syllabus Overview

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