Question 1

Which of the following best explains why water is considered a polar molecule?

Accepted Answer

Because the oxygen atom is more electronegative than hydrogen, creating partial charges and an asymmetrical shape.

Question 2

Which of the following bonds is responsible for holding together the two strands of DNA in the double helix?

Accepted Answer

Hydrogen bonds

Question 3

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-4}$$ M. What is its pH?

Accepted Answer

$$4$$

Question 4

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice form a stable, open lattice that makes ice less dense than liquid water.

Question 5

Which of the following molecules would be most likely to dissolve in water?

Accepted Answer

A polar molecule such as ammonia ($$NH_3)$$

Question 6

What is the main reason water has a high specific heat compared to other substances?

Accepted Answer

The extensive hydrogen bonding between water molecules requires more energy to change temperature.

Question 7

Which of the following statements about hydrogen bonds is TRUE?

Accepted Answer

Hydrogen bonds are noncovalent and do not involve sharing of electrons.

Question 8

A solution with a pH of 5 has how many times more hydrogen ions than a solution with a pH of 7?

Accepted Answer

$$100$$ times more

Question 9

Which property of water allows a water strider to walk on the surface of a pond?

Accepted Answer

Cohesion due to hydrogen bonding

Question 10

Which of the following best describes why salt ($$NaCl) $$dissolves in water?

Accepted Answer

The polar water molecules surround and separate the $$Na^+$$ and $$Cl^-$$ ions.

Question 11

Which of the following is NOT an emergent property of water due to hydrogen bonding?

Accepted Answer

Water’s ability to dissolve nonpolar molecules

Question 12

Which of the following best explains why nonpolar molecules are hydrophobic?

Accepted Answer

They cannot form hydrogen bonds with water molecules.

Question 13

If the pH of a solution changes from 8 to 6, what happens to the hydrogen ion concentration?

Accepted Answer

It increases by 100 times.

Question 14

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers resist changes in pH by accepting or donating hydrogen ions.

Question 15

Which of the following molecules is most likely to have nonpolar covalent bonds?

Accepted Answer

$$CH_4 ($$methane)

Question 16

Which of the following statements about acids and bases is correct?

Accepted Answer

Acids donate $$H^+$$ ions and decrease pH; bases accept $$H^+$$ ions and increase pH.

Question 17

Which of the following best explains why water moderates temperature changes in coastal regions?

Accepted Answer

Water’s high specific heat allows it to absorb and release large amounts of heat with little temperature change.

Question 18

Which of the following is true about the bond between oxygen and hydrogen within a water molecule?

Accepted Answer

It is a polar covalent bond.

Question 19

Which of the following best describes the relationship between pH and hydrogen ion concentration?

Accepted Answer

As pH decreases, hydrogen ion concentration increases.

Question 20

Which of the following is a real-life example of water’s adhesive property?

Accepted Answer

Capillary action pulling water up a plant stem

Water: Structure, Properties, and Biological Importance

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