Question 1

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5.As substances travel from the small intestines to the large intestine,what would happen to the H+ ion concentration?

Accepted Answer

A)  It decreases 100-fold.
B)  It increases by 100-fold.
C)  It increases 10-fold.
D)  It increases 2-fold.
E)  It decreases 10-fold. B

Question 2

Oxygen-16 is abundant and has 8 protons and 8 neutrons.Oxygen-18 has two extra neutrons.These two forms are:

Accepted Answer

A)  oxygen ions.
B)  oxygen isotopes.
C)  oxygen isomers.
D)  oxygen dimers. B

Question 3

To increase the rate of a reaction you could:

Accepted Answer

A)  Add more products.
B)  Decrease the temperature.
C)  Add more reactants.
D)  remove a catalyst C

Question 4

Matter is composed of:

Accepted Answer

A)  atoms
B)  energy
C)  mass
D)  molecules

Question 5

Capillary action is one of the forces that aids water's upward movement in plants.The narrower the diameter of the tube,the farther the water column will rise.Capillary action is a result of water molecules:

Accepted Answer

A)  storing heat and thus moving faster because of heat of vaporization.
B)  producing sufficient surface tension to overcome the pull of gravity.
C)  having a strong cohesive force and attaching to the surrounding vessel walls.
D)  having an adhesive force,which allows them to attach to the vessel walls.
E)  being associated with hydrophobic molecules,which can result in upward movement.

Question 6

Carbon-12,Carbon-13 and Carbon-14 are examples of:

Accepted Answer

A)  ions
B)  isotopes
C)  isomers
D)  molecules

Question 7

Salt is often used to melt ice on roads during the winter because it lowers the freezing/melting point of water.When salt dissolves in water,individual Na+ and Cl- ions break away from the salt lattice and become surrounded by water molecules.Why would this cause ice to melt?

Accepted Answer

A)  Hydrogen bonds are broken,and the salt ions interfere with interactions between H and O.As a result,it is more difficult for water molecules to bond and form ice.
B)  Hydrogen bonds are formed,and the salt ions bond with O.As a result,it is more difficult for water molecules to bond and form ice.
C)  Hydrogen bonds are broken,and the salt ions bond with O and H respectively.As a result,it is more difficult for water molecules to bond and form ice.

Question 8

Regardless of its shape,a given orbital may contain no more than:

Accepted Answer

A)  1 electron.
B)  4 electrons.
C)  8 electrons.
D)  2 electrons.

Question 9

Consider the following electronegativity values: Boron (B)= 1.8
Carbon (C)= 2.5
Chlorine (Cl)= 3.2
Selenium (Se)= 2.6
Which of the following bonds is the most polar?

Accepted Answer

A)  B-Cl
B)  C-Cl
C)  Se-Cl
D)  It cannot be determined from the information provided.

Question 10

Atoms in which the number of electrons does not equal the number of protons are known as:

Accepted Answer

A)  valences.
B)  ions.
C)  isotopes.
D)  isomers.

Question 11

A scientist conducts a procedure that causes nitrogen atoms to gain neutrons.The resulting atoms will be:

Accepted Answer

A)  ions of nitrogen.
B)  positively charged.
C)  negatively charged.
D)  isotopes of nitrogen.
E)  new elements with higher atomic numbers.

Question 12

Two oxygen atoms joined to each other by the sharing of two pairs of electrons form a(n):

Accepted Answer

A)  single bond.
B)  ionic bond.
C)  hydrogen bond.
D)  double covalent bond.

Question 13

Water molecules are polar with ends that exhibit partial positive and negative charges.These opposite charges allow water molecules to attract each other through:

Accepted Answer

A)  ionic bonds.
B)  covalent bonds.
C)  hydrogen bonds.
D)  peptide bonds.

Question 14

Isotopes that are unstable and decay when their nucleus breaks up into elements with lower atomic numbers,emitting significant amounts of energy in the process,are called:

Accepted Answer

A)  energetic
B)  ionic
C)  radioactive
D)  isometric

Question 15

An atom has 20 electrons and 20 neutrons.What is the mass of this atom?

Accepted Answer

A)  10
B)  20
C)  40
D)  80

Question 16

Life is thought to have evolved from complex molecules formed by the interaction of smaller molecules in oceans and the atmosphere.The substance which brought these molecules together to interact is

Accepted Answer

A)  hydrogen.
B)  acids.
C)  water.
D)  buffers.
E)  salts.

Question 17

Because oxygen is more electronegative than hydrogen,the water molecule is:

Accepted Answer

A)  hydrophobic.
B)  hydrophilic.
C)  nonpolar.
D)  ionic.
E)  polar.

Question 18

Sue was monitoring the oil spill into the Gulf of Mexico from an oil tanker.From her observations,she noted that the oil was moving as large patches in the water.It did not appear as though the oil was dissolving into the water.Why did the oil not dissolve into the water?

Accepted Answer

A)  Hydrophobic interactions
B)  Surface tension
C)  Sea water acts as a solvent
D)  Water forms hydration shells
E)  Water has a high heat of vaporization

Question 19

An atom that is negatively charged because it has accepted an electron is a(n):

Accepted Answer

A)  isomer.
B)  ion.
C)  isotope.
D)  monomer.

Question 20

The electronic configuration of the noble gas Neon,which has an atomic number of 10,can be written as follows: 1s22s22p6.What is the electronic configuration of the noble gas Argon,which has an atomic number of 18?

Accepted Answer

A)  1s22s23p64s25p6
B)  1s22s62p23s63p2
C)  1s22s22p63s23p6
D)  1s22s83p8

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

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5.As substances travel from the small intestines to the large intestine,what would happen to the H⁺ ion concentration?