Question 1

Which of the following best describes the law of constant composition?

Accepted Answer

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

Question 2

A sample of water from a river and a sample of water from a laboratory are analyzed and found to contain hydrogen and oxygen in a mass ratio of approximately 1:8. This observation supports which chemical law?

Accepted Answer

Law of constant composition

Question 3

Which experiment provided the first direct evidence for the existence of electrons as subatomic particles?

Accepted Answer

Thomson's cathode ray tube experiment

Question 4

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 5

A sample contains two isotopes of chlorine: $^{35}\mathrm{Cl}$ (mass = 34.97 amu, abundance = 75.8%) and $^{37}\mathrm{Cl}$ (mass = 36.97 amu, abundance = 24.2%). What is the atomic weight of chlorine?

Accepted Answer

$35.45\ \mathrm{amu}$

Question 6

Which of the following is a correct empirical formula for a compound with the molecular formula $C_6H_{12}O_6$?

Accepted Answer

$CH_2O$

Question 7

Which of the following best explains why the mass number of an atom is not listed on the periodic table?

Accepted Answer

The mass number varies due to the presence of isotopes.

Question 8

Which of the following ions is a polyatomic cation?

Accepted Answer

$NH_4^+$

Question 9

What is the correct name for the compound $FeCl_3$?

Accepted Answer

Iron(III) chloride

Question 10

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

Accepted Answer

$Mg_3(PO_4)_2$

Question 11

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 12

Which of the following is a diatomic molecule that occurs naturally?

Accepted Answer

$O_2$

Question 13

What is the correct name for $H_2SO_4$?

Accepted Answer

Sulfuric acid

Question 14

Which of the following best describes a metalloid?

Accepted Answer

An element with properties intermediate between metals and nonmetals

Question 15

Which of the following is the correct name for $N_2O_5$?

Accepted Answer

Dinitrogen pentoxide

Question 16

A sample of a compound contains 12 g of carbon and 32 g of oxygen. What is the empirical formula of the compound?

Accepted Answer

$CO_2$

Question 17

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

Accepted Answer

$(NH_4)_2SO_4$

Question 18

Which of the following is a correct statement about 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 the ratio of small whole numbers.

Question 19

Which of the following is the correct name for $CCl_4$?

Accepted Answer

Carbon tetrachloride

Question 20

Which of the following is the correct name for $CH_3CH_2OH$?

Accepted Answer

Ethanol

Atoms, Molecules, and Atomic Theory: Foundations of Chemistry

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