Question 1

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

Accepted Answer

The oxygen atom in water is more electronegative, causing a partial negative charge near the oxygen and a partial positive charge near the hydrogens.

Question 2

Which property of water allows insects to walk on its surface?

Accepted Answer

Cohesion due to hydrogen bonding

Question 3

A solution is made by dissolving 2 moles of NaCl in 1 liter of water. What is the molarity of the solution? 
$$	ext{Molarity} = \frac{	ext{moles of solute}}{	ext{liters of solution}}$$

Accepted Answer

$$2\ 	ext{M}$$

Question 4

Which of the following is NOT a property of water that is important for life?

Accepted Answer

Water has a low heat capacity.

Question 5

What type of bond forms between the hydrogen atom of one water molecule and the oxygen atom of another water molecule?

Accepted Answer

Hydrogen bond

Question 6

Which scenario best illustrates the hydrophobic effect?

Accepted Answer

Oil droplets clustering together in water

Question 7

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart, making ice less dense.

Question 8

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

Electrons are shared equally between atoms.

Question 9

A student mixes salt (NaCl) in water and observes that the salt dissolves. Which property of water is most responsible for this observation?

Accepted Answer

Versatility as a solvent due to polarity

Question 10

Which of the following statements about hydrogen bonds is TRUE?

Accepted Answer

Hydrogen bonds are responsible for many of water's unique properties.

Question 11

Which of the following best explains why sweating cools the body?

Accepted Answer

Evaporation of water requires energy, which is taken from the body as heat.

Question 12

Which of the following is an example of a chemical reaction?

Accepted Answer

Formation of water from hydrogen and oxygen gases: $$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 13

Which property of water helps moderate Earth's climate?

Accepted Answer

High specific heat

Question 14

Which of the following best describes the role of water in biochemical reactions?

Accepted Answer

Water acts as a solvent, reactant, and product in various reactions.

Question 15

A solution contains 0.5 moles of glucose in 0.25 liters of solution. What is the molarity? 
$$	ext{Molarity} = \frac{	ext{moles of solute}}{	ext{liters of solution}}$$

Accepted Answer

$$2\ 	ext{M}$$

Question 16

Which of the following is a consequence of water’s high heat of vaporization?

Accepted Answer

Evaporation of water cools surfaces efficiently.

Question 17

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve transferring electrons, while covalent bonds involve sharing electrons.

Question 18

Which property of water is most important for transporting nutrients and waste in living organisms?

Accepted Answer

Versatility as a solvent

Question 19

Which of the following is a direct result of water’s polarity?

Accepted Answer

Water can dissolve both polar and ionic substances.

Question 20

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

Accepted Answer

The positive and negative ends of water molecules surround and separate Na+ and Cl- ions.

Chemical Bonds and Properties of Water in Biology

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