Question 1

Which statement best defines an element?

Accepted Answer

A substance that cannot be broken down chemically into other substances.

Question 2

The atomic number of an element is determined by the number of:

Accepted Answer

Protons

Question 3

Isotopes of an element differ in their number of:

Accepted Answer

Neutrons

Question 4

Atoms are chemically reactive primarily because of their:

Accepted Answer

Number of valence electrons

Question 5

Which bond involves the sharing of electrons?

Accepted Answer

Covalent bond

Question 6

A water molecule results because:

Accepted Answer

Oxygen is more electronegative than hydrogen

Question 7

Cohesion between water molecules is primarily due to:

Accepted Answer

Hydrogen bonding

Question 8

Ice floats on liquid water because:

Accepted Answer

Hydrogen bonds stabilize and keep water molecules farther apart in ice than in liquid water.

Question 9

A decrease of pH from 7 to 5 represents a:

Accepted Answer

100-fold increase in $$[H^+]$$ concentration

Question 10

Buffers work by:

Accepted Answer

Accepting or donating hydrogen ions

Question 11

Which of the following best explains why salt (NaCl) dissolves in water?

Accepted Answer

The partial charges on water molecules surround and separate the Na$$^+$$ and Cl$$^-$$ ions.

Question 12

Which property of water allows it to moderate temperature in organisms and environments?

Accepted Answer

High specific heat

Question 13

Which of the following is a trace element essential for human life?

Accepted Answer

Iron (Fe)

Question 14

If a solution has a pH of 3, what is its $$[H^+]$$ concentration?

Accepted Answer

$$[H^+] = 10$$^{-3}$$ M

Question 15

Which scenario best illustrates the concept of electronegativity?

Accepted Answer

Oxygen in a water molecule attracts shared electrons more strongly than hydrogen.

Question 16

Which of the following is NOT a property of water that results from hydrogen bonding?

Accepted Answer

Nonpolar nature

Question 17

A solution with a pH of 9 is:

Accepted Answer

Basic, with a low $$[H^+]$$ concentration

Question 18

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally between atoms

Question 19

Which of the following would most likely disrupt hydrogen bonding in water?

Accepted Answer

Adding a nonpolar substance like oil

Question 20

Which of the following best explains why sweating cools you down?

Accepted Answer

Evaporation of water requires energy, which is taken from your skin as heat.

Campbell Biology – Chapters 2 & 3: The Chemical Context of Life and Water & Life (Practice Questions Study Guide)

Study Guide - Practice Questions