Question 1

Which of the following best describes a chemical property of matter?

Accepted Answer

Iron reacts with oxygen to form rust.

Question 2

Which statement correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound consists of two or more elements chemically bonded in a fixed ratio.

Question 3

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad with lettuce, tomatoes, and cucumbers

Question 4

Which subatomic particle determines the identity of an element?

Accepted Answer

Proton

Question 5

An atom has 17 protons, 18 neutrons, and 17 electrons. What is its mass number?

Accepted Answer

$$35$$

Question 6

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 7

Which element is in Group 2 and Period 3 of the periodic table?

Accepted Answer

Magnesium ($$\mathrm{Mg})$$

Question 8

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

Accepted Answer

They have a full valence electron shell.

Question 9

What is the correct formula for aluminum oxide?

Accepted Answer

$$\mathrm{Al_2O_3}$$

Question 10

Which of the following is a correct Lewis dot structure for chlorine ($$\mathrm{Cl}$$)?

Accepted Answer

$$\mathrm{Cl}$$ with 7 dots around it

Question 11

A neutral atom of sulfur has an atomic number of 16 and a mass number of 32. How many protons, neutrons, and electrons does it have?

Accepted Answer

16 protons, 16 neutrons, 16 electrons

Question 12

Which of the following best describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increased nuclear charge.

Question 13

Which of the following is a chemical change?

Accepted Answer

Burning wood

Question 14

Which of the following elements is most likely to form a $$2^+$$ ion?

Accepted Answer

Magnesium ($$\mathrm{Mg})$$

Question 15

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons; covalent bonds involve the sharing of electrons.

Question 16

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of carbon dioxide ($$\mathrm{$$CO_2$$}$$). How many moles of $$\mathrm{$$CO_2$$}$$ are present?

Accepted Answer

$$0.50$$ moles

Question 17

Which of the following is the correct electron configuration for a neutral atom of sodium ($$\mathrm{Na}$$, atomic number 11)?

Accepted Answer

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

Question 18

Which of the following best explains why fluorine is more reactive than chlorine?

Accepted Answer

Fluorine has a higher electronegativity.

Question 19

Which of the following is the correct name for $$\mathrm{K_2SO_4}$$?

Accepted Answer

Potassium sulfate

Question 20

A patient is given a saline solution containing $$0.90\%$$ sodium chloride ($$\mathrm{NaCl}) by $$mass. Which type of mixture is this solution?

Accepted Answer

Homogeneous mixture

Concepts of Chemistry – Exam #2 Study Guide

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