Question 1

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

Accepted Answer

Iron rusting when exposed to air

Question 2

A student measures the mass of a sample as 12.34 g and its volume as 4.56 mL. What is the density of the sample, reported with the correct number of significant figures?

Accepted Answer

$$2.7\ \mathrm{g/mL}$$

Question 3

Which statement best describes the Law of Definite Proportions?

Accepted Answer

A compound always contains the same elements in the same ratio by mass.

Question 4

Convert $$25.0\ ^\circ\mathrm{C} to $$Kelvin.

Accepted Answer

$$298.15\ \mathrm{K}$$

Question 5

Which of the following is a molecular compound?

Accepted Answer

CO$$_2$$

Question 6

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

Accepted Answer

$$0.500\ \mathrm{mol}$$

Question 7

Which of the following best describes an intensive property?

Accepted Answer

It is independent of the amount of substance present.

Question 8

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

Accepted Answer

CH$$_2O$$

Question 9

Which of the following is the correct formula for magnesium nitrate?

Accepted Answer

Mg(NO$$_3$$)$$_2$$

Question 10

A 10.0 g sample of calcium carbonate decomposes to form calcium oxide and carbon dioxide. If 5.6 g of calcium oxide is produced, what mass of carbon dioxide is released? (Assume the Law of Conservation of Mass applies.)

Accepted Answer

$$4.4\ \mathrm{g}$$

Question 11

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 12

Which of the following is the correct name for H$$_2SO$_4$$?

Accepted Answer

Sulfuric acid

Question 13

A student needs to prepare 250.0 mL of a 0.100 M NaCl solution. How many grams of NaCl are required? ($$M_{NaCl} = 58.44\ \mathrm{g/mol})$$

Accepted Answer

$$1.46\ \mathrm{g}$$

Question 14

Which of the following best describes the Law of Multiple Proportions?

Accepted Answer

When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers.

Question 15

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

Accepted Answer

Al$$_2(SO$_4$$)$$_3$$

Question 16

A sample of glucose (C$$_6H$_{12}O$_6) $$contains $$1.20\ \mathrm{mol} of $$carbon atoms. How many molecules of glucose are present?

Accepted Answer

$$2.00 	imes 10$$^{22}$$

Question 17

Which of the following is a correct example of a physical property?

Accepted Answer

Boiling point of water is $$100\ ^\circ\mathrm{C} at 1 $$atm

Question 18

Which of the following is the correct name for the compound N$$_2O$_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 19

A 2.00 g sample of a compound contains 0.80 g of carbon and 1.20 g of oxygen. What is the mass percent of carbon in the compound?

Accepted Answer

$$40.0\%$$

Question 20

Which of the following is the correct balanced chemical equation for the combustion of methane ($$\mathrm{CH}_4$$)?

Accepted Answer

$$\mathrm{CH}_4 + 2\ \mathrm{O}_2 \rightarrow \mathrm{CO}_2 + 2\ \mathrm{H}_2\mathrm{O}$$

Foundations of General Chemistry: Matter, Atoms, Molecules, and Chemical Equations

Guida di studio - Domande di pratica

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