Question 1

When a sample of potassium chloride dissolves in water, it separates into potassium ions and chloride ions. Which of the following best accounts for the positive charge of the potassium ions?

Accepted Answer

A) They have extra mass. 
B) They have a large volume. 
C) They have fewer electrons than protons. 
D) They have a high density of neutrons and protons.

Question 2

Four different gases are all observed to have the same temperature. Which of the following conclusions is supported by this observation?

Accepted Answer

A) All four gases must have the same mass. 
B) All four gases must have the same pressure. 
C) All four gases must have equal numbers of particles. 
D) All four gases must have equal average kinetic energies.

Question 3

A leaf gently floats on a pond. Which of the following statements best explains why the leaf stays on top of the water?

Accepted Answer

A) The leaf has nonpolar covalent bonds between its atoms. 
B) The density of the leaf is greater than the density of the water. 
C) The water molecules are held tightly together by hydrogen bonding. 
D) The hydrogen and oxygen atoms in the water are chemically bonded.

Question 4

Which of the following occurs when a rigid container of gas is heated?

Accepted Answer

A) The pressure inside the container increases. 
B) The pressure inside the container decreases. 
C) The pressure inside the container stays the same. 
D) The pressure inside the container changes the composition of the gas.

Question 5

Which of the following did scientists learn about the atom from Rutherford's gold foil experiment?

Accepted Answer

A) Atoms combine in simple ratios to form compounds. 
B) Electrons travel around the nucleus of an atom in concentric circular paths. 
C) The mass of an atom and its positive charge are concentrated in the nucleus. 
D) The atomic mass of an atom is equal to the number of protons and neutrons in the nucleus.

Question 6

In a hydrogen fluoride (HF) molecule, a hydrogen atom and a fluorine atom are held together by a polar covalent bond. Which of the following best explains why this bond is polar?

Accepted Answer

A) the large difference in the atomic radii of hydrogen and fluorine atoms 
B) the large difference in the atomic masses of hydrogen and fluorine atoms 
C) the large difference in theelectronegativities of hydrogen and fluorine atoms 
D) the large difference in the number of electrons of hydrogen andfluorine atoms

Question 7

When a sample of potassium chloride dissolves in water, it separates into potassium ions and chloride ions. Which of the following best accounts for the positive charge of the potassium ions?

Accepted Answer

A) They have extra mass. 
B) They have a large volume. 
C) They have fewer electrons than protons. 
D) They have a high density of neutrons and protons.

Question 8

Which of the following did scientists learn about the atom from Rutherford's gold foil experiment?

Accepted Answer

A) Atoms combine in simple ratios to form compounds. 
B) Electrons travel around the nucleus of an atom in concentric circular paths. 
C) The mass of an atom and its positive charge are concentrated in the nucleus. 
D) The atomic mass of an atom is equal to the number of protons and neutrons in the nucleus.

Question 9

Which of the following statements best explains why elements in the same family of the periodic table have similar bonding properties?

Accepted Answer

A) The elements have similar atomic sizes. 
B) The elements have similar atomic masses. 
C) The elements have similar numbers of protons. 
D) The elements have similar valence electron configurations.

Question 10

Which of the following statements applies to a nuclear fission reaction?

Accepted Answer

A) The reaction has no commercial applications. 
B) The reaction takes place only at very high temperatures. 
C) The reaction produces only shortlived radioactive waste. 
D) The reaction releases large amounts of energy when nuclei split apart.

Question 11

A student made a homogeneous mixture of water and salt. Which of the following statements applies to this homogeneous mixture?

Accepted Answer

A) This mixture is a solution. 
B) This mixture is a pure substance. 
C) The salt is not evenly distributed throughout this mixture. 
D) The salt chemically combines with the water in this mixture.

Question 12

Which of the following correctly describes a trend from top to bottom in the group 2 (2A) elements on the periodic table?

Accepted Answer

A) Ionic radius decreases. 
B) Ionic charge increases. 
C) Atomic radius increases. 
D) Atomic number decreases.

Question 13

Which of the following statements explains why oxygen is classified asa pure substance and air is classifiedas a mixture?

Accepted Answer

A) Oxygen is more reactive than air. 
B) Oxygen has a higher density than air. 
C) Oxygen undergoes phase changes, whereas air is always a gas. 
D) Oxygen contains only one substance, but air contains several substances.

Question 14

Which of the following statements explains what happens to the gas inside a balloon as the external pressure on the balloon decreases and the temperature stays constant?

Accepted Answer

A) The volume increases. 
B) The volume decreases. 
C) The molecular speed increases. 
D) The molecular speed decreases.

Question 15

Which of the following helps explain why honey dissolves more rapidly in hot water than in cold water?

Accepted Answer

A) The honey and hot water form more covalent bonds. 
B) The hot water is more chemically reactive with the honey. 
C) The honey breaks down into free atoms more quickly in the hot water. 
D) The greater motion of hot water molecules disperses the honey more quicly.

Question 16

A person left a bottle of distilled water and a bottle of a sugary drink outside overnight. In the morning, one liquid was frozen but the other was not. Which liquid was frozen and why did it freeze?

Accepted Answer

A) The sugary drink froze because solutions are more dense than pure substances. 
B) The distilled water froze because pure substances are more dense than solutions. 
C) The sugary drink froze because solutions have a higher freezing point than pure substances. 
D) The distilled water froze because pure substances have a higher freezing point than solutions.

Question 17

Which of the following explains why saltwater is considered a mixture?

Accepted Answer

A) It is composed of one element. 
B) It is composed of one compound. 
C) It is composed of two or more substances and has new chemical properties. 
D) It is composed of two or more substances that retain their own chemical properties.

Question 18

The final elements produced by radioactive decay differ from the original radioactive elements because the nuclei of the ? nal elements are always

Accepted Answer

A) more stable. 
B) increased in mass. 
C) half as radioactive. 
D) positively charged.

Question 19

Atoms of element A and atoms of element B react to form a compound. In the reaction, the radius of each atom of element A is decreased. Which of the following explains this decrease in atomic radius in the reaction?

Accepted Answer

A) The atoms of element A lose electrons to atoms of element B. 
B) The atoms of element A gain neutrons from atoms of element B. 
C) Nuclear particles are converted into energy in atoms of element A. 
D) Protons become more densely packed in the nuclei of element A atoms.

Question 20

Which of the following statements describes the role of a buffer?

Accepted Answer

A) It increases the rate of a reaction. 
B) It keeps the pH of a solution within a small range. 
C) It changes the oxidation states of elements in a compound. 
D) It shifts the reaction equilibrium to favor more product formation.

Exam 2: Chemistry

When a sample of potassium chloride dissolves in water, it separates into potassium ions and chloride ions. Which of the following best accounts for the positive charge of the potassium ions?

Four different gases are all observed to have the same temperature. Which of the following conclusions is supported by this observation?

A leaf gently floats on a pond. Which of the following statements best explains why the leaf stays on top of the water?

Which of the following occurs when a rigid container of gas is heated?

Which of the following did scientists learn about the atom from Rutherford's gold foil experiment?

In a hydrogen fluoride (HF) molecule, a hydrogen atom and a fluorine atom are held together by a polar covalent bond. Which of the following best explains why this bond is polar?

When a sample of potassium chloride dissolves in water, it separates into potassium ions and chloride ions. Which of the following best accounts for the positive charge of the potassium ions?

Which of the following did scientists learn about the atom from Rutherford's gold foil experiment?

Which of the following statements best explains why elements in the same family of the periodic table have similar bonding properties?

Which of the following statements applies to a nuclear fission reaction?

A student made a homogeneous mixture of water and salt. Which of the following statements applies to this homogeneous mixture?

Which of the following correctly describes a trend from top to bottom in the group 2 (2A) elements on the periodic table?

Which of the following statements explains why oxygen is classified asa pure substance and air is classifiedas a mixture?

Which of the following statements explains what happens to the gas inside a balloon as the external pressure on the balloon decreases and the temperature stays constant?

Which of the following helps explain why honey dissolves more rapidly in hot water than in cold water?

A person left a bottle of distilled water and a bottle of a sugary drink outside overnight. In the morning, one liquid was frozen but the other was not. Which liquid was frozen and why did it freeze?

Which of the following explains why saltwater is considered a mixture?

The final elements produced by radioactive decay differ from the original radioactive elements because the nuclei of the ? nal elements are always

Atoms of element A and atoms of element B react to form a compound. In the reaction, the radius of each atom of element A is decreased. Which of the following explains this decrease in atomic radius in the reaction?

Which of the following statements describes the role of a buffer?