Deck 2: Atoms and Molecules: the Chemical Basis of Life

Question 1

What differentiates an organic compound from an inorganic compound?

A) An organic compound lacks isotopes.
B) An organic compound contains carbon.
C) An organic compound lacks valence electrons.
D) An organic compound is basic rather than acidic.
E) An organic compound contains two or more atoms.

Answer 1

B

Question 2

What is the difference between a stable isotope and a radioisotope?

A) A stable isotope emits light.
B) A radioisotope emits radiation.
C) A stable isotope emits radiation.
D) A stable isotope absorbs radiation.
E) A radioisotope has an unequal number of protons and electrons.

Answer 2

B

Question 3

Which substance is a reactant in the following chemical equation? CO₂ + H₂O ↔ H₂CO₃

A) water
B) carbon
C) oxygen
D) hydrogen
E) carbonic acid

Answer 3

A

Question 4

A chlorine atom has 17 protons and 18 neutrons. What is its atomic mass?

A) 1 amu
B) 17 amu
C) 18 amu
D) 35 amu
E) 306 amu

Question 5

Figure 2-1 ​

What is the difference between the two atoms in the accompanying figure?

A) their electrical charge
B) the number of electrons
C) the number of protons
D) the number of neutrons
E) the number of valence shells

Question 6

How many molecules are present in one mole of C₆H₁₂O₆?

A) 1.7 × 10¹⁰ molecules
B) 1.3 × 10¹⁰ molecules
C) 24 molecules
D) 1.7 × 10²² molecules
E) 6.02 × 10²³ molecules

Question 7

Sulfur has six valence electrons. How many covalent bonds does a sulfur atom typically form?

A) 3
B) 1
C) 5
D) 2
E) 4

Question 8

Isotopes differ from each other with respect to the number of:

A) protons only
B) electrons only
C) neutrons only
D) both protons and electrons
E) both neutrons and protons

Question 9

How can we identify a particular element?

A) by its number of protons
B) by its number of electrons
C) by its number of neutrons
D) by its shape of valence shells
E) by its amount of energy levels

Question 10

Figure 2-1 ​

What does the accompanying figure represent?

A) an acid and a base
B) two different ions
C) a cation and an anion
D) two different elements
E) two isotopes of the same element

Question 11

Figure 2-1 ​

What is the atomic mass of the atom identified as A in the accompanying figure?

A) 2 amu
B) 6 amu
C) 8 amu
D) 12 amu
E) 18 amu

Question 12

The chemical behavior of an atom is determined most directly by the:

A) atomic number
B) atomic weight
C) number of neutrons
D) number protons
E) number of valence electrons

Question 13

The representation H−O−H is known as a(n):

A) structural formula
B) simplest formula
C) molecular formula
D) Lewis structure
E) orbital diagram

Question 14

Which statement best describes the product of a chemical reaction?

A) It is joined by an ionic bond only.
B) It is always in equilibrium with the reactants.
C) It is the substance that initiates the reaction.
D) It is generally written on the left side of the equation.
E) It is the substance generated by the reaction.

Question 15

Nitrogen has five electrons in its valence shell. How many electrons does it need to gain to complete its valence shell?

A) one
B) two
C) three
D) seven
E) eight

Question 16

Which statement best describes an atom?

A) A substance that cannot burn.
B) A substance that is soluble in both acid and base
C) A substance that is held together by covalent bonds
D) A substance that is composed of more than one kind of atom
E) A substance that cannot be broken into a simpler substance

Question 17

What is the atomic mass of the most common isotope of carbon?

A) 12.01 amu
B) 20.18 amu
C) 16.01 amu
D) 1.01 amu
E) 14.01 amu

Question 18

Which of the following atoms can form five covalent bonds?

A) oxygen
B) phosphorus
C) hydrogen
D) carbon
E) nitrogen

Question 19

Which element activates many enzymes and is needed in blood and other tissues of animals?

A) magnesium
B) iron
C) sulfur
D) chlorine
E) sodium

Question 20

Which of the following is a covalent compound?

A) potassium chloride
B) methane
C) lithium bromide
D) magnesium oxide
E) sodium fluoride

Question 21

Which of the following would most likely form electrolytes in water?

A) glucose
B) ethanol
C) an organic compound
D) an inorganic compound
E) a nonionic compound

Question 22

As water boils and turns to steam, what happens to the hydrogen bonds?

A) The hydrogen bonds break.
B) The hydrogen bonds strengthen.
C) The hydrogen bonds generate additional bonds.
D) The hydrogen bonds form a crystalline lattice structure.
E) The hydrogen bonds continually break and rejoin.

Question 23

Which component becomes oxidized in the following chemical reaction? 4 Fe + 3 O₂ → 2 Fe₂O₃

A) rust
B) iron
C) water
D) oxygen
E) hydrogen

Question 24

Which statement about van der Waal interactions is false ?

A) They are very strong.
B) They are attractive forces.
C) They operate over very short distances.
D) They form between nonpolar molecules.
E) They involve transient regions of positive and negative charges.

Question 25

Which of the following is a common oxidizing agent?

A) carbon monoxide
B) lithium
C) oxygen
D) zinc
E) iron

Question 26

The cohesiveness between water molecules is due largely to _________.

A) ionic bonds
B) hydrogen bonds
C) polar covalent bonds
D) nonpolar covalent bonds
E) hydrophobic interactions

Question 27

It takes one calorie of heat to raise the temperature of one gram of water by one degree Celsius at sea level. This is referred to as the ____ of water.

A) specific heat
B) heat of fusion
C) homeostasis
D) vaporization
E) heat of transformation

Question 28

Which of the following solutions has a pH value of 9.0?

A) Beer
B) Blood
C) Bleach
D) Seawater
E) Rainwater

Question 29

___________ in the muscle cell are required for muscle contraction.

A) Sodium ions
B) Potassium ions
C) Calcium ions
D) Chloride ions
E) Magnesium ions

Question 30

Water molecules have a strong tendency to stick to one another, a property known as ___________.

A) adhesion
B) capillary action
C) cohesion
D) surface tension
E) osmosis

Question 31

Consider the aquatic insects pictured in the accompanying figure. Which characteristic of water molecules directly contributes to their remarkable "water walking" success? ​

​

A) ionic bonds
B) capillary action
C) hydrogen bonds
D) adhesive forces
E) nonpolar covalent bonds

Question 32

Which component is the oxidizing agent in the following chemical reaction? 4 Fe + 3 O₂ → 2 Fe₂O₃

A) rust
B) iron
C) water
D) oxygen
E) hydrogen

Question 33

Which event illustrates evaporative cooling?

A) a tea kettle whistling
B) sweat evaporating from the skin
C) ice cubes floating in a glass of water
D) a fish not freezing in an ice-covered pond
E) salt dissolving in a pot of water with potatoes

Question 34

What is the specific heat of water?

A) 0.5 cal/g of water per degree Celsius
B) 0.75 cal/g of water per degree Celsius
C) 3 cal/g of water per degree Celsius
D) 1 cal/g of water per degree Celsius
E) 2 cal/g of water per degree Celsius

Question 35

Sugar dissolves readily in water because it is a(n) ____ substance.

A) adhesive
B) cohesive
C) hydrophilic
D) hydrophobic
E) evaporative

Question 36

Which atom would most likely be involved in an ionic bond?

A) hydrogen
B) oxygen
C) sodium
D) nitrogen
E) helium

Question 37

What is the difference between an electrically neutral atom and an ion?

A) An ion has an unequal number of protons and electrons, while a neutral atom has an equal number.
B) An ion has an equal number of protons and electrons, while an atom has an unequal number.
C) An atom has an unequal number of neutrons and protons, while an ion has an equal number.
D) An atom has its electrons in orbitals, while an ion has its electrons in its nucleus.
E) An atom must have an equal number of neutrons and electrons, while an ion does not.

Question 38

A base is defined as a(n) _____ acceptor.

A) neutron
B) electron
C) proton
D) anion
E) cation

Question 39

The covalent bond between a hydrogen atom and the oxygen atom in water is formed when:

A) hydrogen gains an electron from oxygen
B) hydrogen and oxygen share an electron pair
C) hydrogen and oxygen both lose electrons from their outer shells
D) hydrogen and oxygen both gain electrons in their outer shells
E) hydrogen loses an electron from oxygen

Question 40

What is the OH− concentration of a solution having a pH of 2?

A) 1 × 10^-12
B) 1 × 10^-10
C) 1 × 10^-7
D) 1 × 10^-2
E) 1 × 10^-1

Question 41

When a small amount of hydrochloric acid (HCl) is added to a solution of Na₂HPO₄, the pH of the solution does not change markedly. The pH also does not change drastically when a small amount of sodium hydroxide (NaOH) is added to this same solution. Based on these observations, the compound Na₂HPO₄ is:

A) acting as a buffer
B) acting as a solvent
C) able to donate hydrogen atoms to HCl
D) able to remove hydrogen ions from the OH− of NaOH
E) an enzyme facilitating the reaction between HCl and NaOH

Question 42

Diagram and carefully label two water molecules using an appropriately sized ball for each atom. Then, use a dashed line on this diagram to show how hydrogen bonds form between the two water molecules.

Question 43

The atomic mass determines the identity of an element.

Question 44

When atoms react to form an ionic bond, electrons are shared between those atoms.

Question 45

An inorganic compound is one that contains carbon.

Question 46

A salt is a compound in which the hydrogen ion of ____ is replaced by some other cation.

A) water
B) a base
C) an acid
D) an anion
E) a hydroxide ion

Question 47

An atom that has a filled valence shell is stable and unreactive.

Question 48

An example of an anion is K⁺.

Question 49

List four of the principal chemical elements found in living organisms and identify an important biological function of each element.

Question 50

Oxidation occurs when an atom gains one or more electrons.

Question 51

Identify and compare the properties of the bond between sodium and chloride (NaCl) with the bond between carbon and hydrogen in methane (CH₄).

Question 52

A chemical formula shows the types and numbers of atoms in a molecule and their arrangement.

Question 53

What is the approximate pH of ammonia?

A) 2
B) 4
C) 7
D) 8
E) 11

Question 54

The tetrahedron shape of a methane molecule is the result of orbital hybridization.

Question 55

Which substance is an example of a very strong acid?

A) milk
B) coffee
C) bleach
D) seawater
E) lemon juice

Question 56

Which element forms the backbone of organic molecules?

A) magnesium
B) iron
C) chlorine
D) sodium
E) carbon

Question 57

The valence shell of hydrogen or helium is unstable when it contains two electrons.

Question 58

A liquid with a pH of 7 is considered a(n) ____ solution.

A) basic
B) acidic
C) neutral
D) hydrophilic
E) hydrochloric

Question 59

Explain how the number and arrangement of valence electrons is related to the chemical properties of an atom. Use two specific examples in your explanation.

Question 60

What is the purpose of a buffer?

A) To convert an acid to a base
B) To minimize the change in pH
C) To measure the acidity of a solution
D) To form a stable bond between atoms
E) To maintain a constant internal temperature

Question 62

A solution having a pH of 8 is slightly acidic .

Question 67

A calorie is the amount of heat energy required to raise the temperature of 1 g of water 1 degree Celsius (C).

Question 69

Specific heat refers to the amount of energy required to change 1 gram of a substance from the liquid phase to the vapor phase.

Question 70

Explain and identify the mechanism of how carbon dioxide maintains blood pH levels.

Question 71

A combination of adhesive and cohesive forces accounts for surface tension.

Question 72

As a researcher, you are charged with determining the effects of a new drug. From previous observations, you suspect that this drug reduces the rate of DNA production (replication) in the skin cells of patients using the drug. With the following materials, design an experiment that would determine the effect of the drug on DNA replication. You know that DNA contains phosphate groups. You have radioactive isotopes of phosphate (³²P), skin cell cultures from different patients, the drug in question, and a device that measures radioactivity.

Question 74

The hydrogen bonds of water play an important role in the ability of plants to transport water (via capillary action). Explain how this occurs.