Question 1

According to Aristotle, every flammable material consisted of

Accepted Answer

A)  earth and fire. 
B)  phlogiston. 
C)  oxygen and earth. 
D)  air and heat. 
A)  earth and fire. 
B)  phlogiston. 
C)  oxygen and earth. 
D)  air and heat. A

Question 2

Chemical reactions that give off energy are called

Accepted Answer

A)  endothermic. 
B)  exothermic. 
C)  activated. 
D)  oxidation-reduction. 
A)  endothermic. 
B)  exothermic. 
C)  activated. 
D)  oxidation-reduction. B

Question 3

Which of the following compounds is not classed as an oxide?

Accepted Answer

A)  CO2 
B)  SiO2 
C)  BaSO4 
D)  H2O 
A)  CO2 
B)  SiO2 
C)  BaSO4 
D)  H2O C

Question 4

When a metal is oxidized, the resulting oxide

Accepted Answer

A)  has less mass than the original metal. 
B)  has the same mass as the original metal. 
C)  has more mass than the original metal. 
D)  Any of these choices could be correct, depending on the metal. 
A)  has less mass than the original metal. 
B)  has the same mass as the original metal. 
C)  has more mass than the original metal. 
D)  Any of these choices could be correct, depending on the metal.

Question 5

An enzyme is a

Accepted Answer

A)  gasoline additive that reduces pollution. 
B)  constituent of natural gas. 
C)  solvent used in electrolysis. 
D)  biological catalyst. 
A)  gasoline additive that reduces pollution. 
B)  constituent of natural gas. 
C)  solvent used in electrolysis. 
D)  biological catalyst.

Question 6

A chemical equilibrium occurs when the

Accepted Answer

A)  mass of the products equals the mass of the reactants. 
B)  number of molecules of the products equals the number of molecules of the reactants. 
C)  concentration of the products equals the concentration of the reactants. 
D)  speed of the forward reaction equals the speed of the reverse reaction. 
A)  mass of the products equals the mass of the reactants. 
B)  number of molecules of the products equals the number of molecules of the reactants. 
C)  concentration of the products equals the concentration of the reactants. 
D)  speed of the forward reaction equals the speed of the reverse reaction.

Question 7

Sulfur has an atomic mass of 32 u and Avogadro's number is 6 × 1023 formula units/mole. The number of sulfur atoms in 1 mole of sulfur is

Accepted Answer

A)  32. 
B)  1.9 × 1022. 
C)  6 × 1023. 
D)  1.9 × 1025. 
A)  32. 
B)  1.9 × 1022. 
C)  6 × 1023. 
D)  1.9 × 1025.

Question 8

The yield of the product C in the reversible reaction A + B C + energy will decrease if

Accepted Answer

A)  the temperature decreases. 
B)  the temperature increases. 
C)  the surface area of the substances increases. 
D)  the catalyst is changed appropriately. 
A)  the temperature decreases. 
B)  the temperature increases. 
C)  the surface area of the substances increases. 
D)  the catalyst is changed appropriately.

Question 9

Which of the following statements about ozone is incorrect?

Accepted Answer

A)  The formula of ozone is O3. 
B)  Ozone molecules are more stable than those of ordinary oxygen. 
C)  At low altitudes ozone contributes to smog. 
D)  At high altitudes ozone absorbs solar ultraviolet radiation. 
A)  The formula of ozone is O3. 
B)  Ozone molecules are more stable than those of ordinary oxygen. 
C)  At low altitudes ozone contributes to smog. 
D)  At high altitudes ozone absorbs solar ultraviolet radiation.

Question 10

The speed of a chemical reaction is not affected by

Accepted Answer

A)  the surface area of the reactants. 
B)  catalysts. 
C)  the concentration of reactants. 
D)  the type of bond in reaction products. 
A)  the surface area of the reactants. 
B)  catalysts. 
C)  the concentration of reactants. 
D)  the type of bond in reaction products.

Question 11

A storage battery stores

Accepted Answer

A)  electrons. 
B)  electric current. 
C)  energy. 
D)  voltage. 
A)  electrons. 
B)  electric current. 
C)  energy. 
D)  voltage.

Question 12

Whether a chemical reaction is endothermic or exothermic depends on

Accepted Answer

A)  the bond energies of the reactants. 
B)  the bond energies of the products. 
C)  both of the above energies. 
D)  neither of the above energies. 
A)  the bond energies of the reactants. 
B)  the bond energies of the products. 
C)  both of the above energies. 
D)  neither of the above energies.

Question 13

The scientist whose experiments showed that tin, upon heating, combined with a gas from the air was

Accepted Answer

A)  Priestley. 
B)  Stahl. 
C)  Lavoisier. 
D)  Becher. 
A)  Priestley. 
B)  Stahl. 
C)  Lavoisier. 
D)  Becher.

Question 14

Oxidation-reduction reactions involve the transfer between the reacting substances of

Accepted Answer

A)  electrons. 
B)  H+ ions. 
C)  O2- ions. 
D)  O2 molecules. 
A)  electrons. 
B)  H+ ions. 
C)  O2- ions. 
D)  O2 molecules.

Question 15

An example of an exothermic process is the

Accepted Answer

A)  dissociation of a salt in water solution. 
B)  neutralization of an acid by a base. 
C)  electrolysis of water. 
D)  melting of ice. 
A)  dissociation of a salt in water solution. 
B)  neutralization of an acid by a base. 
C)  electrolysis of water. 
D)  melting of ice.

Question 16

An oxide decomposed by heating will give

Accepted Answer

A)  oxygen and another element. 
B)  CO2 and water. 
C)  oxygen ions and metal ions. 
D)  a metal and water. 
A)  oxygen and another element. 
B)  CO2 and water. 
C)  oxygen ions and metal ions. 
D)  a metal and water.

Question 17

An example of slow oxidation is

Accepted Answer

A)  a lighted candle. 
B)  the rusting of iron. 
C)  the lighting of a match. 
D)  a log burning in a fireplace. 
A)  a lighted candle. 
B)  the rusting of iron. 
C)  the lighting of a match. 
D)  a log burning in a fireplace.

Question 18

The number of moles of O2 needed to react with 10 moles of C2H2 in the reaction 2C2H2 + 5O2 → 4CO2 + 2H2O is

Accepted Answer

A)  5. 
B)  10. 
C)  25. 
D)  50. 
A)  5. 
B)  10. 
C)  25. 
D)  50.

Question 19

One mole of which of the following compounds contains the largest number of fluorine atoms?

Accepted Answer

A)  HF 
B)  SF2 
C)  BF3 
D)  XeF6 
A)  HF 
B)  SF2 
C)  BF3 
D)  XeF6

Question 20

If a certain reaction is endothermic, the reverse reaction

Accepted Answer

A)  cannot occur. 
B)  may occur spontaneously. 
C)  cannot occur spontaneously. 
D)  absorbs energy. 
A)  cannot occur. 
B)  may occur spontaneously. 
C)  cannot occur spontaneously. 
D)  absorbs energy.

According to Aristotle, every flammable material consisted of

Chemical reactions that give off energy are called

Which of the following compounds is not classed as an oxide?

When a metal is oxidized, the resulting oxide

An enzyme is a

A chemical equilibrium occurs when the

Sulfur has an atomic mass of 32 u and Avogadro's number is 6 × 10²³ formula units/mole. The number of sulfur atoms in 1 mole of sulfur is

The yield of the product C in the reversible reaction A + B C + energy will decrease if

Which of the following statements about ozone is incorrect?

The speed of a chemical reaction is not affected by

A storage battery stores

Whether a chemical reaction is endothermic or exothermic depends on

The scientist whose experiments showed that tin, upon heating, combined with a gas from the air was

Oxidation-reduction reactions involve the transfer between the reacting substances of

An example of an exothermic process is the

An oxide decomposed by heating will give

An example of slow oxidation is

The number of moles of O₂ needed to react with 10 moles of C₂H₂ in the reaction 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O is

One mole of which of the following compounds contains the largest number of fluorine atoms?

If a certain reaction is endothermic, the reverse reaction

The Scientific Method

Motion

Energy

Energy and the Future

Matter and Heat

Electricity and Magnetism

Waves

The Nucleus

The Atom

The Periodic Law

Crystals, Ions, and Solutions

Organic Chemistry

Atmosphere and Hydrosphere

The Rock Cycle

The Evolving Earth

The Solar System

The Stars

The Universe Galaxies

Filters

Exam 12: Chemical Reactions

According to Aristotle, every flammable material consisted of

Chemical reactions that give off energy are called

Which of the following compounds is not classed as an oxide?

When a metal is oxidized, the resulting oxide

An enzyme is a

A chemical equilibrium occurs when the

Sulfur has an atomic mass of 32 u and Avogadro's number is 6 × 1023 formula units/mole. The number of sulfur atoms in 1 mole of sulfur is

The yield of the product C in the reversible reaction A + B C + energy will decrease if

Which of the following statements about ozone is incorrect?

The speed of a chemical reaction is not affected by

A storage battery stores

Whether a chemical reaction is endothermic or exothermic depends on

The scientist whose experiments showed that tin, upon heating, combined with a gas from the air was

Oxidation-reduction reactions involve the transfer between the reacting substances of

An example of an exothermic process is the

An oxide decomposed by heating will give

An example of slow oxidation is

The number of moles of O2 needed to react with 10 moles of C2H2 in the reaction 2C2H2 + 5O2 → 4CO2 + 2H2O is

One mole of which of the following compounds contains the largest number of fluorine atoms?

If a certain reaction is endothermic, the reverse reaction

The Scientific Method

Motion

Energy

Energy and the Future

Matter and Heat

Electricity and Magnetism

Waves

The Nucleus

The Atom

The Periodic Law

Crystals, Ions, and Solutions

Organic Chemistry

Atmosphere and Hydrosphere

The Rock Cycle

The Evolving Earth

The Solar System

The Stars

The Universe Galaxies

Filters

Sulfur has an atomic mass of 32 u and Avogadro's number is 6 × 10²³ formula units/mole. The number of sulfur atoms in 1 mole of sulfur is

The number of moles of O₂ needed to react with 10 moles of C₂H₂ in the reaction 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O is