Question 1

A sample of chlorine gas contains two naturally occurring isotopes: $$^{35}\mathrm{Cl} (75.78$$%, mass = 34.969 amu) and $$^{37}\mathrm{Cl} (24.22$$%, mass = 36.966 amu). What is the average atomic mass of chlorine?

Accepted Answer

$$35.45$$ amu

Question 2

Which of the following best describes a chemical property?

Accepted Answer

The ability of iron to rust when exposed to air

Question 3

A student measures the mass of a metal cylinder as $$12.45 g $$and its volume as $$4.50 mL. $$What is the density of the cylinder?

Accepted Answer

$$2.77 g/mL$$

Question 4

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

Salad dressing with oil and vinegar

Question 5

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

Accepted Answer

$$0.500$$ mol

Question 6

Which of the following statements about isotopes is TRUE?

Accepted Answer

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

Question 7

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

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 8

Which of the following is a physical change?

Accepted Answer

Ice melting to form liquid water

Question 9

A student needs to prepare $$250.0 mL of a$$ $$0.200 M $$NaCl solution. How many grams of NaCl are required? (Molar mass of NaCl = $$58.44 g/$$mol)

Accepted Answer

$$2.92 g$$

Question 10

Which of the following best explains why water is considered a compound and not a mixture?

Accepted Answer

Water has a fixed ratio of hydrogen to oxygen atoms chemically bonded together.

Question 11

A sample of magnesium contains $$1.20 	imes 10$$^{24}$$ atoms. What is the mass of this sample? (Molar mass of Mg = 24.31$ g/mol, Avogadro's number = 6.022$$ 	imes $$10^{23}$$ atoms/mol)

Accepted Answer

$$48.4 g$$

Question 12

Which of the following is the correct name for $$\mathrm{N}_2\mathrm{O}_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 13

Which of the following is NOT a postulate of Dalton's atomic theory?

Accepted Answer

Atoms can be divided into protons, neutrons, and electrons.

Question 14

A $$5.00 g $$sample of an unknown metal is placed in a graduated cylinder containing $$10.0 mL of $$water. The water level rises to $$12.5 mL. $$What is the density of the metal?

Accepted Answer

$$2.0 g/mL$$

Question 15

Which of the following elements is a metalloid?

Accepted Answer

Silicon

Question 16

A student is asked to convert $$250 mL to $$liters. What is the correct answer?

Accepted Answer

$$0.250 L$$

Question 17

Which of the following best describes the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 18

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

Accepted Answer

$$\mathrm{Al}_2(\mathrm{SO}_4)_3$$

Question 19

A $$10.0 g $$sample of calcium carbonate decomposes to form $$4.4 g of $$carbon dioxide and $$5.6 g of $$calcium oxide. Which law does this experiment best illustrate?

Accepted Answer

Law of conservation of mass

Question 20

Which of the following is a correct statement about ions?

Accepted Answer

An anion is an atom that has gained one or more electrons.

General Chemistry: Foundations, Atoms, Elements, Molecules, and Compounds – Study Guide

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