Biology (Raven), 10th Edition

Chapter 2: The Nature of Molecules and the Properties of Water

Post-Test

1
A buffer exerts its effects because:
A)It absorbs or releases H+ ions reversibly to resist a pH change within its buffering range.
B)It releases H+ when the pH drops.
C)It absorbs H+ when the pH rises.
D)All of the above explain buffering effects.
E)None of the above explains buffering effects.
2
The atomic weight of an atom
A)equals the number of protons plus the number of neutrons.
B)equals the number of protons plus the number of electrons.
C)equals the number of neutrons.
D)changes after each reaction.
E)changes randomly with time.
3
An atom having an atomic number of 12 needs how many electrons to be electrically neutral?
A)6
B)9
C)12
D)24
E)15
4
An element can be easily identified by the number of
A)electrons.
B)protons.
C)neutrons.
D)bonds.
E)orbitals
5
Isotopes of a given element have
A)the same atomic number but different weights.
B)the same atomic weight but different atomic numbers.
C)different atomic numbers and weights.
D)the same number of neutrons.
E)have different atomic numbers.
6
The isotope 14C has
A)14 electrons.
B)6 electrons.
C)8 neutrons.
D)6 electrons and 8 neutrons.
7
The difference between 12C and 14C is
A)2 electrons.
B)2 protons.
C)2 neutrons.
D)2 carbon atoms.
E)2 ionic bonds.
8
If neutral atoms become positive ions, they
A)gain electrons.
B)lose electrons.
C)gain protons.
D)lose neutrons.
E)gain neutrons.
9
A chlorine atom has 7 electrons in the outermost shell. Potassium, with 1 electron in the outermost shell, will react with how many chlorine atoms?
A)5
B)3
C)1
D)2
E)0
10
An ion is an atom or molecule that
A)is in a gaseous state.
B)has less neutrons than protons.
C)that emits neutrons.
D)forms covalent bonds.
E)carries an electrical charge.
11
Molecules form because of
A)the shape of the individual atoms.
B)an attraction between neutrons.
C)transfer or sharing of electrons.
D)a drive toward solubility.
E)electron to electron attraction.
12
A covalent bond is
A)an example of a bond that results in ionic compounds.
B)the transfer of electrons from one atom to another.
C)a sharing of electrons between two atoms.
D)an attraction of charged atoms.
E)the weakest from of atomic interaction.
13
In a solution that is basic, the number of
A)OH- is less than the number of H+.
B)OH- cancels out the number of H+.
C)H+ is the same as the number of OH-.
D)H+ is greater than the number of OH-.
E)OH- is greater than the number of H+.
14
Which of these is not true regarding chemical reactions?
A)The extent to which chemical reactions occur is influenced by temperature.
B)Chemical reactions involve the formation and breaking of chemical bonds.
C)The extent to which chemical reactions occur is influenced by the concentration of reactant and products.
D)The extent to which chemical reactions occur is influenced by catalysts.
E)Reactions in nature are not reversible.
15
Hydrogen bonding in water causes water to
A)boil at a lower temperature than expected.
B)be less dense as ice than as liquid water.
C)absorb heat with a lot of change in temperature.
D)release heat with a lot of change in temperature.
E)shrink as temperature approaches 0°C.
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