Question 1

Which of the following best explains why water molecules are able to form hydrogen bonds with each other?

Accepted Answer

Water molecules are polar, with partial positive charges on hydrogen and partial negative charges on oxygen.

Question 2

A gecko is able to climb smooth vertical surfaces due to which type of weak chemical interaction?

Accepted Answer

Van der Waals interactions

Question 3

Which element makes up the largest percentage of body mass in humans, according to Table 2.1?

Accepted Answer

Oxygen

Question 4

What is the atomic mass of an oxygen atom with 8 protons and 10 neutrons?

Accepted Answer

18

Question 5

Which of the following best describes the difference between a nonpolar covalent bond and a polar covalent bond?

Accepted Answer

Nonpolar covalent bonds involve equal sharing of electrons, while polar covalent bonds involve unequal sharing.

Question 6

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$pH = 5$$

Question 7

Which property of water allows a spider to walk on its surface, as shown in the image?

Accepted Answer

Cohesion and surface tension

Question 8

What is the main reason ice floats on water?

Accepted Answer

Ice is less dense than liquid water due to stable hydrogen bonds.

Question 9

Which of the following is a trace element required by humans in minute quantities?

Accepted Answer

Iron

Question 10

What is the product of the concentrations of $$[H^+]$$ and $$[OH^-] in $$pure water at 25°C?

Accepted Answer

$$[H^+][OH^-] = 10$$^{-14}$$

Question 11

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

Accepted Answer

Buffers minimize changes in concentrations of $$H^+$$ and $$OH^-$$ ions.

Question 12

Which of the following is an example of a chemical reaction important for life, as shown in the study materials?

Accepted Answer

$$6 CO_2$ + 6 H_2O \rightarrow C_6H_{12}O_6$ + 6 O_2$

Question 13

Which of the following best describes the difference between a solute, a solvent, and a solution?

Accepted Answer

A solute is the substance dissolved, a solvent is the dissolving agent, and a solution is the homogeneous mixture.

Question 14

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

Accepted Answer

Acids increase the $$H^+$$ concentration, while bases reduce the $$H^+$$ concentration.

Question 15

Which emergent property of water is most directly responsible for the moderation of coastal temperatures, as shown in the map image?

Accepted Answer

High specific heat

Question 16

If a molecule has a molecular mass of 18 daltons, how many molecules are present in 1 mole of this substance?

Accepted Answer

$$6.02 	imes 10$$^{23}$$

Question 17

Which of the following best explains why oil does not mix with water?

Accepted Answer

Oil molecules are hydrophobic and have nonpolar bonds.

Question 18

Which of the following is true about ionic bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another, resulting in oppositely charged ions.

Question 19

A tomato sauce has an $$[H^+]$$ concentration of $$1 	imes 10$$^{-5}$$ M. What is the $$[OH^-]$$ concentration?

Accepted Answer

$$1 	imes 10$$^{-9}$$ M

The Chemical Context of Life & Water: Foundations for Biological Processes

Study Guide - Practice Questions