$$\frac{12.0}{44.0} \times 100 = 27.3\%$$

Question 1

Which of the following best describes a mixture of sand and salt?

Accepted Answer

A heterogeneous mixture

Question 2

Which element is a transition metal according to the periodic table provided?

Accepted Answer

Iron (Fe)

Question 3

A sample of a liquid has a mass of 25.0 g and a volume of 20.0 mL. What is its density?

Accepted Answer

$$d = \frac{m}{V} = \frac{25.0\ \mathrm{g}}{20.0\ \mathrm{mL}} = 1.25\ \mathrm{g/mL}$$

Question 4

Which of the following is the correct electron configuration for a neutral atom of sodium (Na)?

Accepted Answer

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

Question 5

Which of the following ions is polyatomic?

Accepted Answer

$$\mathrm{NO}_3^-$$

Question 6

A radioactive isotope undergoes beta decay. Which of the following correctly describes the change in the nucleus?

Accepted Answer

A neutron is converted into a proton, increasing the atomic number by 1

Question 7

Which of the following best describes the molecular shape of ammonia ($$\mathrm{NH}_3$$)?

Accepted Answer

Trigonal pyramidal

Question 8

How many moles are in 18.0 grams of water ($$\mathrm{H}_2\mathrm{O}$$)? (Molar mass of $$\mathrm{H}_2\mathrm{O} = 18.0\ \mathrm{g/mol})$$

Accepted Answer

$$\frac{18.0\ \mathrm{g}}{18.0\ \mathrm{g/mol}} = 1.00\ \mathrm{mol}$$

Question 9

Which of the following is the correct formula for ammonium sulfate?

Accepted Answer

$$\mathrm{(NH_4$)_2SO_4}$$

Question 10

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

Accepted Answer

$$0.500\ \mathrm{mol}$$

Question 11

Which of the following statements about metals and nonmetals is correct?

Accepted Answer

Metals tend to lose electrons and form cations

Question 12

Which of the following is the correct balanced equation for the reaction of sodium with chlorine gas to form sodium chloride?

Accepted Answer

$$2\mathrm{Na} + \mathrm{Cl}_2 \rightarrow 2\mathrm{NaCl}$$

Question 13

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

Accepted Answer

A chemical change results in the formation of new substances, while a physical change does not

Question 14

Which of the following is the correct name for $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 15

What is the percent by mass of carbon in carbon dioxide ($$\mathrm{CO}_2$$)? (Atomic masses: C = 12.0, O = 16.0)

Accepted Answer

$$\frac{12.0}{44.0} 	imes 100 = 27.3\%$$

Question 16

Which of the following is the correct Lewis structure for water ($$\mathrm{H}_2\mathrm{O}$$)?

Accepted Answer

O atom in the center with two single bonds to H atoms and two lone pairs on O

Question 17

Which of the following best describes the energy change when a ball is dropped from a height?

Accepted Answer

Potential energy is converted to kinetic energy

Question 18

Which of the following is the correct formula for the polyatomic ion sulfate?

Accepted Answer

$$\mathrm{SO}_4$$^{2-}$$

Question 19

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 20

A sample of a radioactive isotope has a half-life of 3 hours. If you start with 80.0 g, how much remains after 9 hours?

Accepted Answer

10.0 g

General Chemistry I: Core Concepts and Study Guide

Guida di studio - Domande di pratica