Question 1

Which of the following is broken when water evaporates?

Accepted Answer

A)   nonpolar covalent bonds
B)   ionic bonds
C)   hydrogen bonds
D)   polar covalent bonds C

Question 2

Which of the following is the best description of an atom's physical structure?

Accepted Answer

A)   An atom is a solid mass of material.
B)   The particles that form an atom are equidistant from each other.
C)   Atoms are little bubbles of space with mass concentrated at the center of the bubble.
D)   Atoms are little bubbles of space with mass concentrated on the outside surface of the bubble. C

Question 3

What is the difference between covalent bonds and ionic bonds?

Accepted Answer

A)   Covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms.
B)   Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms.
C)   Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between charged atoms.
D)   Covalent bonds involve the transfer of electrons between charged atoms; ionic bonds involve the sharing of electrons between atoms. B

Question 4

What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms?

Accepted Answer

A)   two
B)   four
C)   six
D)   eight

Question 5

How many electron pairs are shared between carbon atoms in a molecule that has the formula C₂H₄?

Accepted Answer

A)   one
B)   two
C)   three
D)   four

Question 6

We can represent atoms by listing the number of protons, neutrons, and electrons-for example, 2p⁺, 2n⁰, 2e⁻ for helium. Which of the following represents the ¹⁸O isotope of oxygen?

Accepted Answer

A)   7p⁺, 2n⁰, 9e⁻
B)   8p⁺, 10n⁰, 8e⁻
C)   9p⁺, 9n⁰, 9e⁻
D)   10p⁺, 8n⁰, 9e⁻

Question 7

Which of the following are compounds?

Accepted Answer

A)   H₂O, O₂, and CH₄
B)   H₂O and O₂
C)   O₂ and CH₄
D)   H₂O and CH₄, but not O₂

Question 8

Refer to the following figure to answer the questions below.
 
-If an atom has a charge of +1, which of the following must be true?

Accepted Answer

A)   It has two more protons than neutrons.
B)   It has the same number of protons as electrons.
C)   It has one more electron than it does protons.
D)   It has one more proton than it does electrons.

Question 9

Refer to the following figure to answer the questions below.
 
-How many electrons are involved in a triple covalent bond?

Accepted Answer

A)   3
B)   6
C)   9
D)   12

Question 10

Which one of the atoms shown would be most likely to form a cation with a charge of +1?

Accepted Answer

A)   
B)   
C)   
D)

Question 11

Compared with ³¹P, the radioactive isotope ³²P has

Accepted Answer

A)   a different atomic number.
B)   one more proton.
C)   one more electron.
D)   one more neutron.

Question 12

Refer to the following figure to answer the questions below.
 
-You are asked to indicate the type and number of atoms in a molecule. Which representation would work best?

Accepted Answer

A)   molecular formula
B)   structural formula
C)   ball-and-stick model
D)   space-filling model

Question 13

A covalent bond is likely to be polar when ________.

Accepted Answer

A)   one of the atoms sharing electrons is more electronegative than the other atom
B)   the two atoms sharing electrons are equally electronegative
C)   carbon is one of the two atoms sharing electrons
D)   the two atoms sharing electrons are of the same elements

Question 14

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

Accepted Answer

A)   calcium
B)   iodine
C)   sodium
D)   phosphorus

Question 15

A salamander relies on hydrogen bonding to stick to various surfaces. Therefore, a salamander would have the greatest difficulty clinging to a ________.

Accepted Answer

A)   slightly damp surface
B)   surface of hydrocarbons
C)   surface of mostly carbon-oxygen bonds
D)   surface of mostly carbon-nitrogen bonds

Question 16

Which of the following statements correctly describes any chemical reaction that has reached equilibrium?

Accepted Answer

A)   The concentrations of products and reactants are equal.
B)   The reaction is now irreversible.
C)   Both forward and reverse reactions have halted.
D)   The rates of the forward and reverse reactions are equal.

Question 17

Refer to the following figure to answer the questions below.
 
-What causes the shape of the molecule shown?

Accepted Answer

A)   the shape of the two p orbitals in the carbon atom
B)   the shape of the one s orbital in the carbon atom
C)   the shape of the sp³ hybrid orbitals of the electrons shared between the carbon and hydrogen atoms
D)   hydrogen bonding configurations between the carbon and hydrogen atoms

Question 18

Which bond or interaction would be difficult to disrupt when compounds are put into water?

Accepted Answer

A)   covalent bonds between carbon atoms
B)   hydrogen bonds
C)   ionic bonds
D)   ionic and hydrogen bonds

Question 19

Carbon-14 has the same ________.

Accepted Answer

A)   atomic number and atomic mass as carbon-12
B)   atomic number and thus number of neutrons as carbon-13
C)   atomic mass as both carbon-12 and carbon-13
D)   number of protons but more neutrons than carbon-12

Question 20

Refer to the following figure to answer the questions below.
 
-Nitrogen (N)normally forms three covalent bonds with a valence of five. However, ammonium has four covalent bonds, each to a different hydrogen (H)atom (H has a valence of one). What do you predict to be the charge on ammonium?

Accepted Answer

A)   +1
B)   -1
C)   +2
D)   -2

Exam 2: The Chemical Context of Life