Question 1

When stirred in 30°C water, 5 g of powdered potassium bromide, KBr, dissolves faster than 5 g of large crystals of potassium bromide. Which of the following best explains why the powdered KBr dissolves faster?

Accepted Answer

A) Powdered potassium bromide exposes more surface area to water molecules than large crystals of potassium bromide. 
B) Potassium ions and bromide ions in the powder are smaller than potassium ions and bromide ions in the large crystals. 
C) Fewer potassium ions and bromide ions have been separated from each other in the powder than in the crystals. 
D) Powdered potassium bromide is less dense than large crystals of potassium bromide.

Question 2

Which of the following is the same for both hydrogen and potassium?

Accepted Answer

A) atomic mass 
B) total mass of neutrons 
C) number of valence electrons 
D) number of ?lled energy levels

Question 3

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 4

One way that mixtures differ from pure substances is in the methods that can be used to separate them into their components.Which of the following is a method used to separate the components of some mixtures?

Accepted Answer

A) a nuclear reaction 
B) a filtration process 
C) a chemical reaction 
D) an electrolysis process

Question 5

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

Accepted Answer

A) an ionic bond, because electrons transfer from one element to the other 
B) a nonpolar covalent bond, because the elements share electrons equally 
C) a polar covalent bond, because the elements do not share electrons equally 
D) an intermolecular force, because the elements do not form a chemical bond

Question 6

Which of the following samples of sugar will dissolve fastest in a pitcher of lemonade?

Accepted Answer

A) 5 g of cubed sugar in 5°C lemonade 
B) 5 g of cubed sugar in 20°C lemonade 
C) 5 g of granulated sugar in 5°C lemonade 
D) 5 g of granulated sugar in 20°C lemonade

Question 7

Which of the following statements best explains why potassium (K) reacts easily with bromine (Br)?

Accepted Answer

A) Potassium and bromine both have valence electrons in the fourth energy level. 
B) Potassium and bromine have the same number of electrons in their highest energy levels. 
C) Potassium has one electron in its highest energy level, and bromine needs one electron to complete its highest energy level. 
D) Potassium needs one electron to complete its highest energy level, and bromine has an extra electron in its highest energy level.

Question 8

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

Accepted Answer

A) an ionic bond, because electrons transfer from one element to the other 
B) a nonpolar covalent bond, because the elements share electrons equally 
C) a polar covalent bond, because the elements do not share electrons equally 
D) an intermolecular force, because the elements do not form a chemical bond

Question 9

Which of the following correctly pairs a phase of matter with its description?

Accepted Answer

A) Solid: Particles have no motion. 
B) Liquid: Particles expand to fill any container in which they are placed. 
C) Gas: Particles have higher amounts of energy than when in the liquid phase. 
D) Liquid: Particles are more strongly attached to one another than when in the solid phase.

Question 10

Which of the following characteristics allows blood to resist changes in pH?

Accepted Answer

A) acidity 
B) basicity 
C) buffering capacity 
D) clotting factors

Question 11

Which of the following statements explains how a buffer maintains pH when small amounts of a strong base are added?

Accepted Answer

A) The salt in the buffer absorbs the base. 
B) The water in the buffer dilutes the base. 
C) The weak acid of the buffer neutralizes the base. 
D) The weak base of the buffer neutralizes the base.

Question 12

The pH of four different solutions of common materials is measured. Which of the following lists the solutions in order from most acidic to most basic?

Accepted Answer

A) battery acid, lemon juice, blood, laundry detergent 
B) lemon juice, battery acid, blood, laundry detergent 
C) laundry detergent, blood, lemon juice, battery acid 
D) battery acid, blood, laundry detergent, lemon juice

Question 13

Which of the following correctly describes molecules of two different gases if they are at the same temperature and pressure?

Accepted Answer

A) They must have the same mass. 
B) They must have the same velocity. 
C) They must have the same average kinetic energy. 
D) They must have the same average potential energy.

Question 14

Which of the following statements best explains why potassium (K) reacts easily with bromine (Br)?

Accepted Answer

A) Potassium and bromine both have valence electrons in the fourth energy level. 
B) Potassium and bromine have the same number of electrons in their highest energy levels. 
C) Potassium has one electron in its highest energy level, and bromine needs one electron to complete its highest energy level. 
D) Potassium needs one electron to complete its highest energy level, and bromine has an extra electron in its highest energy level.

Question 15

Which of the following is an example of nuclear fusion?

Accepted Answer

A) Hydrogen-1 and hydrogen-2 combine to form helium-3. 
B) Polonium-210 decays into lead-206 and an alpha particle. 
C) Carbon-14 breaks down into a beta particle and nitrogen-14. 
D) Uranium-235 and a neutron produce barium-141, krypton-92, and three neutrons.

Question 16

Which of the following observed properties is most reliable in classifying a substance as a metal?

Accepted Answer

A) good conductor of heat 
B) low melting temperature 
C) unreactive with other elements 
D) crumbles when hit by a hammer

Question 17

Which of the following statements describes the elements in family 16 of the periodic table?

Accepted Answer

A) They have six valence electrons. 
B) They are all gases at room temperature. 
C) They exist commonly as cations in nature. 
D) They combine easily with elements in family 17.

Question 18

Which of the following statements explains why elements of the alkali metal family are highly reactive?

Accepted Answer

A) Alkali metals are easily ionized. 
B) Alkali metals are negatively charged. 
C) Alkali metals have an odd number of protons. 
D) Alkali metals have an odd number of electrons.

Question 19

Which of the following pieces of evidence best supports Bohr's idea that electrons occupy specific energy levels within an atom?

Accepted Answer

A) Sodium atoms become positive ions when they lose electrons. 
B) Each element emits a unique brightline spectrum when it falls from an excited state to a ground state. 
C) Beryllium atoms bombarded with alpha particles produce beams that are not influenced by magnetic fields. 
D) Each element has physical and chemical properties that are unique to that element and different from those of other elements.

Question 20

Which of the following sections of the periodic table contains only metals?

Accepted Answer

A) group 2 
B) group 18 
C) period 2 
D) period 6

Exam 2: Chemistry

When stirred in 30°C water, 5 g of powdered potassium bromide, KBr, dissolves faster than 5 g of large crystals of potassium bromide. Which of the following best explains why the powdered KBr dissolves faster?

Which of the following is the same for both hydrogen and potassium?

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

One way that mixtures differ from pure substances is in the methods that can be used to separate them into their components.Which of the following is a method used to separate the components of some mixtures?

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

Which of the following samples of sugar will dissolve fastest in a pitcher of lemonade?

Which of the following statements best explains why potassium (K) reacts easily with bromine (Br) ?

Two elements in a molecule have the same electronegativity values. Which of the following most likely holds the elements together and why?

Which of the following correctly pairs a phase of matter with its description?

Which of the following characteristics allows blood to resist changes in pH?

Which of the following statements explains how a buffer maintains pH when small amounts of a strong base are added?

The pH of four different solutions of common materials is measured. Which of the following lists the solutions in order from most acidic to most basic?

Which of the following correctly describes molecules of two different gases if they are at the same temperature and pressure?

Which of the following statements best explains why potassium (K) reacts easily with bromine (Br) ?

Which of the following is an example of nuclear fusion?

Which of the following observed properties is most reliable in classifying a substance as a metal?

Which of the following statements describes the elements in family 16 of the periodic table?

Which of the following statements explains why elements of the alkali metal family are highly reactive?

Which of the following pieces of evidence best supports Bohr's idea that electrons occupy specific energy levels within an atom?

Which of the following sections of the periodic table contains only metals?