AP Biology Properties of Water

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

• hydrogen bonds.

• nonpolar covalent bonds

• polar covalent bonds.

• ionic bonds.

• van der Waals interactions

Tags

NGSS.MS-PS1-1

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

• a covalent bond

• a hydrogen bond

• an ionic bond

• a hydrophilic bond

• a hydrophobic bond

An example of a hydrogen bond is the bond between

• C and H in methane (CH4).

• the H of one water molecule and the O of another water molecule.

• Na+and Cl- in salt.

• the two hydrogen atoms in a molecule of hydrogen gas (H2).

• Mg+and Cl- in MgCl2.

Water is able to form hydrogen bonds because

• oxygen has a valence of 2.

• the water molecule is shaped like a tetrahedron.

• the bonds that hold together the atoms in a water molecule are polar covalent bonds.

• the oxygen atom in a water molecule has a weak positive charge.

• each of the hydrogen atoms in a water molecule is weakly negative in charge.

What gives rise to the cohesiveness of water molecules?

• hydrophobic interactions

• nonpolar covalent bonds

• ionic bonds

• hydrogen bonds

• both A and C

Tags

NGSS.HS-PS1-3

Which of the following effects is produced by the high surface tension of water?

• Lakes don't freeze solid in winter, despite low temperatures.

• A water strider can walk across the surface of a small pond.

• Organisms resist temperature changes, although they give off heat due to chemical reactions.

• Water can act as a solvent.

• The pH of water remains exactly neutral

The bonds that are broken when water vaporizes are

• ionic bonds.

• hydrogen bonds between water molecules.

• covalent bonds between atoms within water molecules.

• polar covalent bonds.

• nonpolar covalent bonds

Tags

NGSS.MS-PS1-4

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?

• water's change in density when it condenses

• water's ability to dissolve molecules in the air

• the release of heat by the formation of hydrogen bonds

• the absorption of heat by the breaking of hydrogen bonds

• water's high surface tension

Tags

NGSS.MS-PS3-4

Buffers are substances that help resist shifts in pH by

• releasing H+ in acidic solutions

• donating H+ to a solution when they have been depleted.

• releasing OH- in basic solutions.

• accepting H+ when the are in excess.

• Both B and D are correct

Which of the following statements is true about buffer solutions?

• They maintain a constant pH when bases are added to them but not when acids are added to them.

• They maintain a constant pH when acids are added to them but not when bases are added to them.

• They maintain a constant pH of exactly 7 in all living cells and biological fluids

• They maintain a relatively constant pH when either acids or bases are added to them.

• They are found only in living systems and biological fluids.