Question 1

Which statement best summarizes the essence of chemical evolution?

Accepted Answer

A)  Entropy increased. 
B)  Instead of being radiated back to space, energy in the form of sunlight or heat was retained in the oceans and atmosphere. 
C)  An increasing number of exothermic reactions occurred. 
D)  Energy in the form of sunlight or heat was transformed into chemical energy. 
A)  Entropy increased. 
B)  Instead of being radiated back to space, energy in the form of sunlight or heat was retained in the oceans and atmosphere. 
C)  An increasing number of exothermic reactions occurred. 
D)  Energy in the form of sunlight or heat was transformed into chemical energy.

Question 2

How many electrons are involved in a single covalent bond?

Accepted Answer

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

Question 3

Chemical evolution refers to which of the following?

Accepted Answer

A)  Water condensed to form the first oceans. 
B)  Earth's crust solidified, even as massive bombardment from outer space continued. 
C)  Small molecules reacted to form larger, more complex molecules. 
D)  Large molecules tended to break apart because of the intense sunlight and heat from volcanoes. 
A)  Water condensed to form the first oceans. 
B)  Earth's crust solidified, even as massive bombardment from outer space continued. 
C)  Small molecules reacted to form larger, more complex molecules. 
D)  Large molecules tended to break apart because of the intense sunlight and heat from volcanoes.

Question 4

Why is carbon so important in biology?

Accepted Answer

A)  It is a common element on Earth. 
B)  It has very little electronegativity, making it a good electron donor. 
C)  It forms up to four covalent bonds. 
D)  It bonds to only a few other elements. 
A)  It is a common element on Earth. 
B)  It has very little electronegativity, making it a good electron donor. 
C)  It forms up to four covalent bonds. 
D)  It bonds to only a few other elements.

Question 5

When are atoms most stable?

Accepted Answer

A)  when all electrons are paired 
B)  when they have the fewest possible valence electrons 
C)  when all of the electron orbitals in the valence shell are filled 
D)  when they have the maximum number of unpaired electrons 
A)  when all electrons are paired 
B)  when they have the fewest possible valence electrons 
C)  when all of the electron orbitals in the valence shell are filled 
D)  when they have the maximum number of unpaired electrons

Question 6

If an atom has a charge of - 2, which of the following must be true?

Accepted Answer

A)  It has two more protons than neutrons. 
B)  It has two more neutrons than electrons. 
C)  It has two more electrons than protons. 
D)  It has two more protons than electrons. 
A)  It has two more protons than neutrons. 
B)  It has two more neutrons than electrons. 
C)  It has two more electrons than protons. 
D)  It has two more protons than electrons.

Question 7

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by what type of bond or interaction?

Accepted Answer

A)  nonpolar covalent bonds 
B)  ionic bonds 
C)  van der Waals interaction 
D)  polar covalent bonds 
E)  hydrogen bonds 
A)  nonpolar covalent bonds 
B)  ionic bonds 
C)  van der Waals interaction 
D)  polar covalent bonds 
E)  hydrogen bonds

Question 8

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?

Accepted Answer

A)  single and double only 
B)  four single bonds only 
C)  single, double, or triple 
D)  two double bonds only 
A)  single and double only 
B)  four single bonds only 
C)  single, double, or triple 
D)  two double bonds only

Question 9

When one of the atoms involved in a covalent bond has a much higher electronegativity than the other atom, what type of bond results?

Accepted Answer

A)  a polar covalent bond 
B)  a nonpolar covalent bond 
C)  a double bond 
D)  a hydrogen bond 
A)  a polar covalent bond 
B)  a nonpolar covalent bond 
C)  a double bond 
D)  a hydrogen bond

Question 10

Why do chemical reactions tend to speed up when the concentration of the reactants is increased?

Accepted Answer

A)  The reactants have greater energy. 
B)  The reactants move faster. 
C)  The reactants collide more often. 
D)  All of the above apply. 
A)  The reactants have greater energy. 
B)  The reactants move faster. 
C)  The reactants collide more often. 
D)  All of the above apply.

Question 11

Why do chemical reactions tend to speed up when the reactants are heated?

Accepted Answer

A)  The reactants have greater energy. 
B)  The reactants collide more often. 
C)  The reactants move faster. 
D)  All of the above apply. 
A)  The reactants have greater energy. 
B)  The reactants collide more often. 
C)  The reactants move faster. 
D)  All of the above apply.

Question 12

During chemical evolution, which of the following occurred in the molecules involved?

Accepted Answer

A)  Entropy decreased while potential energy increased. 
B)  Entropy stayed constant while potential energy increased. 
C)  Entropy increased while potential energy increased. 
A)  Entropy decreased while potential energy increased. 
B)  Entropy stayed constant while potential energy increased. 
C)  Entropy increased while potential energy increased.

Question 13

Why would the spontaneous formation of formaldehyde and hydrogen cyanide not take place on Earth today as much as on the prebiotic Earth?

Accepted Answer

A)  Atmospheric conditions on Earth, such as the presence of oxygen, have changed. 
B)  The sun has changed its output. 
C)  Microorganisms break these down immediately. 
A)  Atmospheric conditions on Earth, such as the presence of oxygen, have changed. 
B)  The sun has changed its output. 
C)  Microorganisms break these down immediately.

Question 14

How many electrons are involved in a triple covalent bond?

Accepted Answer

A)  two 
B)  three 
C)  six 
D)  nine 
A)  two 
B)  three 
C)  six 
D)  nine

Question 15

Why are some reactions exothermic?

Accepted Answer

A)  The products have higher entropy are more disordered) than the reactants. 
B)  They are spontaneous. 
C)  The products have lower potential energy than the reactants. 
D)  They are nonspontaneous. 
A)  The products have higher entropy are more disordered) than the reactants. 
B)  They are spontaneous. 
C)  The products have lower potential energy than the reactants. 
D)  They are nonspontaneous.

Question 16

The difference between a polar covalent bond and an ionic bond is that electrons are shared unequally in a polar covalent bond, but are completely transferred i.e., not shared) in an ionic bond.

Accepted Answer

A) True 
 B)False

Question 17

A pH of 7 is neutral due to the dissociation of water molecules in pure water. How many molecules of water have broken down into a hydroxide ion and a hydronium ion at pH 7?

Accepted Answer

A)  1 in 1 million 
B)  1 in 10 million 
C)  1 in 100 million 
D)  1 in 1 billion 
A)  1 in 1 million 
B)  1 in 10 million 
C)  1 in 100 million 
D)  1 in 1 billion

Question 18

Water molecules are able to form hydrogen bonds with which of the following?

Accepted Answer

A)  compounds that have nonpolar covalent bonds 
B)  compounds that have polar covalent bonds 
C)  methane gas CH4) molecules 
D)  oxygen gas O2) molecules 
E)  compounds that are not soluble in water 
A)  compounds that have nonpolar covalent bonds 
B)  compounds that have polar covalent bonds 
C)  methane gas CH4) molecules 
D)  oxygen gas O2) molecules 
E)  compounds that are not soluble in water

Question 19

Consider the following reaction at equilibrium: CO2 + H2O -H2CO3. What would be the effect of adding additional H2CO3?

Accepted Answer

A)  Nothing would happen, because the reactants and products are in equilibrium. 
B)  The amounts of CO2 and H2O would decrease. 
C)  It would drive the equilibrium dynamics to the right. 
D)  It would drive the equilibrium dynamics to the left. 
A)  Nothing would happen, because the reactants and products are in equilibrium. 
B)  The amounts of CO2 and H2O would decrease. 
C)  It would drive the equilibrium dynamics to the right. 
D)  It would drive the equilibrium dynamics to the left.

Question 20

Why is water such a good solvent?

Accepted Answer

A)  It can participate in hydrogen bonds. 
B)  Most polar and charged substances dissolve in it. 
C)  It is highly polar. 
D)  All of the above apply. 
A)  It can participate in hydrogen bonds. 
B)  Most polar and charged substances dissolve in it. 
C)  It is highly polar. 
D)  All of the above apply.

Exam 2: Water and Carbon: the Chemical Basis of Life

Which statement best summarizes the essence of chemical evolution?

How many electrons are involved in a single covalent bond?

Chemical evolution refers to which of the following?

Why is carbon so important in biology?

When are atoms most stable?

If an atom has a charge of - 2, which of the following must be true?

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by what type of bond or interaction?

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?

When one of the atoms involved in a covalent bond has a much higher electronegativity than the other atom, what type of bond results?

Why do chemical reactions tend to speed up when the concentration of the reactants is increased?

Why do chemical reactions tend to speed up when the reactants are heated?

During chemical evolution, which of the following occurred in the molecules involved?

Why would the spontaneous formation of formaldehyde and hydrogen cyanide not take place on Earth today as much as on the prebiotic Earth?

How many electrons are involved in a triple covalent bond?

Why are some reactions exothermic?

The difference between a polar covalent bond and an ionic bond is that electrons are shared unequally in a polar covalent bond, but are completely transferred i.e., not shared) in an ionic bond.

A pH of 7 is neutral due to the dissociation of water molecules in pure water. How many molecules of water have broken down into a hydroxide ion and a hydronium ion at pH 7?

Water molecules are able to form hydrogen bonds with which of the following?

Consider the following reaction at equilibrium: CO2 + H2O -H2CO3. What would be the effect of adding additional H2CO3?

Why is water such a good solvent?

Biology and the Tree of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Lipids, Membranes, and the First Cells

Inside the Cell

Energy and Enzymes

Cellular Respiration and Fermentation

Photosynthesis

Cellcell Interactions

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, Rna Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

The Molecular Revolution: Biotechnology and Beyond

Gene Structure and Development

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Algae and Land Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Viruses

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, Signals, and Responses

Plant Reproduction and Development

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Animal Nervous Systems

Animal Sensory Systems

Animal Movement

Chemical Signals in Animals

Animal Reproduction and Development

The Immune System in Animals

An Introduction to Ecology

Behavioural Ecology

Population Ecology

Community Ecology

Ecosystems and Global Ecology

Biodiversity and Conservation Biology

Filters

Consider the following reaction at equilibrium: CO₂+ H₂O -H₂CO₃. What would be the effect of adding additional H₂CO₃?