Unit Review

Question 1 of 26

Which set of coefficients balances this equation?

A. 2, 2, 1

B. 1, 1, 1

C. 2, 1, 2

D. 1, 2, 2

Question 2 of 26

This equation:

A. Represents a chemical reaction

B. Represents the formation of ethane and hydrogen from methane

C. Is balanced

D. All of the above

Question 3 of 26

A ____________ is a substance made up of two or more different substances that are chemically combined in a definite ratio.

A. Compound

B. Mixture

C. Element

D. Solution

Question 4 of 26

Which additional product balances this reaction?

A. 4OH

B. CH₄

C. H₂O₂

D. 2H₂O

Question 5 of 26

This image represents_____________.

A. A methane molecule

B. The structural formula for methane

C. The element carbon

D. A chemical reaction

Question 6 of 26

This image represents _____________.

A. A methane molecule

B. The structural formula for methane

C. The element carbon

D. A chemical reaction

Question 7 of 26

Incomplete combustion contributes to air pollution by _______________.

A. Increasing emissions of unburned volatile organic compounds

B. Increasing emissions of particulate matter and carbon monoxide

C. Increasing the potential for forming ground-level ozone

D. All of the above

Question 8 of 26

When molecules of the alkane family burn, we know the reactions are exothermic because ____________________.

A. Bonds are broken

B. Heat is released

C. Energy must be continuously supplied to sustain the reaction

D. All of the above

Question 9 of 26

This equation shows what substances are present, but not the amount of each substance. This is an example of a ______.

A. Skeleton equation

B. Formulaic equation

C. Constant equation

D. Simple equation

Question 10 of 26

Atoms form chemical bonds by sharing their outer-shell electrons. How many electrons can an atom of carbon share?

A. Eight, because a carbon atom has eight electrons

B. Any number, because carbon atoms form bonds in chains

C. Two, because carbon has two electrons in its outer shell

D. Four, because carbon has four electrons in its outer shell

Question 11 of 26

Which of the following describes a chemical reaction?

A. Chemical reactions yield one or more products that are different from the reactants.

B. Chemical reactions involve energy changes

C. Chemical reactions involve the breaking or formation of chemical bonds

D. All of the above

Question 12 of 26

In a certain chemical reaction, one of the hydrogen atoms in a methane molecule is replaced by the carbon atom of a second methane molecule. Which equation below is the balanced equation for this reaction?

A. CH₄ + CH₄ --> C₂H₆ + 2H₂

B. CH₄ + CH₄ --> C₂H₆+ H₂

C. CH₄ + CH₄ --> C₂H₈

D. CH₄ + CH₄ --> 2CH₄

Question 13 of 26

The formula O₂ represents _____ oxygen.

A. An alloy of

B. A salt of

C. A molecule of

D. The element

Question 14 of 26

When this equation is balanced, the coefficient for carbon dioxide is:

A. 35

B. 4

C. 19

D. 16

Question 15 of 26

If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?

A. The molecular structure of the products will be more complex than that of the reactants.

B. The molecular structure of the reactants will be more complex than that of the products.

C. The total mass of the products will equal the total mass of the reactants.

D. The products will be in a different physical phase than the reactants.

Question 16 of 26

A chemical formula like C₃H₈ is a shorthand way of representing __________.

A. A mixture

B. An element

C. A compound

D. A chemical reaction

Question 17 of 26

Chemical symbols are __________________.

A. A shorthand way to represent elements

B. Used to distinguish one group of elements from another

C. Used to classify elements

D. Used only in the United States

Question 18 of 26

The chemical equation 2H₂ + O₂ represents:

A. 2 atoms of hydrogen and 2 atoms of oxygen

B. 4 atoms of hydrogen and 4 atoms of oxygen

C. 2 atoms of hydrogen and 4 atoms of oxygen

D. 4 atoms of hydrogen and 2 atoms of oxygen

Question 19 of 26

A balanced chemical equation shows that in a chemical reaction _______________,

A. Some new atoms may be created

B. Some atoms may be destroyed

C. Atoms are rearranged

D. The coefficients remain the same

Question 20 of 26

A chemical formula represents the atoms in:

A. An element

B. A compound

C. A solute

D. A mixture

Question 21 of 26

How many atoms are represented in the formula 3H₂O₂?

A. Seven

B. Eight

C. Twelve

D. Eleven

Question 22 of 26

If a hydrocarbon material started burning, what are the likely by-products?

A. Hydrocarbons don't burn

B. C₃H₈O₂

C. H₂O and CO₂

D. NOx

Question 23 of 26

Which alkane has the formula C₁₀H₂₂?

A. Ethane

B. Decane

C. Octane

D. Pentane

Question 24 of 26

What is the simplest hydrocarbon?

A. Methane

B. Ethane

C. Propane

D. Butane

Question 25 of 26

Alkanes all have a certain skeleton formula. Suppose the number of carbon atoms in an alkane is "n". What is the formula of that alkane?

A. C_nH_2n

B. C_nH_n

C. C_nH_2n-2

D. C_nH_2n+2

Question 26 of 26

Which substance is a product of the complete combustion of a fuel?

A. C

B. CO₂

C. CO

D. O₂

Unit Review

Question 1 of 26

Which set of coefficients balances this equation?

Question 2 of 26

This equation:

Question 3 of 26

A ____________ is a substance made up of two or more different substances that are chemically combined in a definite ratio.

Question 4 of 26

Which additional product balances this reaction?

Question 5 of 26

This image represents_____________.

Question 6 of 26

This image represents _____________.

Question 7 of 26

Incomplete combustion contributes to air pollution by _______________.

Question 8 of 26

When molecules of the alkane family burn, we know the reactions are exothermic because ____________________.

Question 9 of 26

This equation shows what substances are present, but not the amount of each substance. This is an example of a ______.

Question 10 of 26

Atoms form chemical bonds by sharing their outer-shell electrons. How many electrons can an atom of carbon share?

Question 11 of 26

Which of the following describes a chemical reaction?

Question 12 of 26

In a certain chemical reaction, one of the hydrogen atoms in a methane molecule is replaced by the carbon atom of a second methane molecule. Which equation below is the balanced equation for this reaction?

Question 13 of 26

The formula O2 represents _____ oxygen.

Question 14 of 26

When this equation is balanced, the coefficient for carbon dioxide is:

Question 15 of 26

If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?

Question 16 of 26

A chemical formula like C3H8 is a shorthand way of representing __________.

Question 17 of 26

Chemical symbols are __________________.

Question 18 of 26

The chemical equation 2H2 + O2 represents:

Question 19 of 26

A balanced chemical equation shows that in a chemical reaction _______________,

Question 20 of 26

A chemical formula represents the atoms in:

Question 21 of 26

How many atoms are represented in the formula 3H2O2?

Question 22 of 26

If a hydrocarbon material started burning, what are the likely by-products?

Question 23 of 26

Which alkane has the formula C10H22?

Question 24 of 26

What is the simplest hydrocarbon?

Question 25 of 26

Alkanes all have a certain skeleton formula. Suppose the number of carbon atoms in an alkane is "n". What is the formula of that alkane?

Question 26 of 26

Which substance is a product of the complete combustion of a fuel?

Your Review Results

The formula O₂ represents _____ oxygen.

A chemical formula like C₃H₈ is a shorthand way of representing __________.

The chemical equation 2H₂ + O₂ represents:

How many atoms are represented in the formula 3H₂O₂?

Which alkane has the formula C₁₀H₂₂?