Biol112 Si

Hydrophobic substances such as vegetable oil are

• nonpolar substances that repel water molecules

• nonpolar substances that have an attraction for water molecules

• polar substances that repel water molecules

• polar substances that have an affinity for water

• charged molecules that hydrogen-bond with water molecules

Why does ice float in liquid water?

• The high surface tension of liquid water keeps the ice on top

• The ionic bonds between the molecules in ice prevent the ice from sinking

• Ice always has air bubbles that keep it afloat

• Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

• The crystalline lattice of ice causes it to be denser than liquid 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

A strong acid like HCl

• ionizes completely in an aqueous solution

• increases the pH when added to an aqueous solution

• reacts with strong bases to create a buffered solution

• is a strong buffer at low pH

• both ionizes completely in aqueous solutions and is a strong buffer at low pH

Which of the following ionizes completely in solution and is considered to be a strong base (alkali)?

• NaCl

• HCl

• NH3

• H2CO3

• NaOH

Tags

NGSS.HS-PS1-1

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 relatively constant pH of approximately 7 when either acids or bases are added to them

• 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

If a solution has a pH of 7, this means that

• there are no H+ ions in the water

• this is a solution of pure water

• the concentration of H+ ions in the water equals the concentration of OH- ions in the water

• this is a solution of pure water, and the concentration of H+ ions in the water is 10-7 M

• this is a solution of pure water, and the concentration of H+ ions equals the concentration of OH- ions in the water

How would acidification of seawater affect marine organisms?

• Acidification would increase dissolved carbonate concentrations and promote faster growth of corals and shell-building animals

• Acidification would decrease dissolved carbonate concentrations and promote faster growth of corals and shell-building animals

• Acidification would increase dissolved carbonate concentrations and hinder growth of corals and shell-building animals

• Acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals

• Acidification would increase dissolved bicarbonate concentrations, and cause increased calcification of corals and shellfish

Tags

NGSS.HS-LS2-5

Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely

• positively charged

• negatively charged

• without charge

• hydrophobic

• nonpolar

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.HS-PS1-3