Question 1

Which of the following best describes the difference between an ionic and a covalent bond?

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another, while covalent bonds involve the sharing of electrons between atoms.

Question 2

Which of the following is an example of a nonpolar covalent molecule?

Accepted Answer

Oxygen gas ($$O_2)$$

Question 3

Which property of water allows it to moderate Earth's climate by absorbing and releasing heat with only slight temperature changes?

Accepted Answer

High specific heat capacity

Question 4

A solution has a pH of 3. Which of the following best describes this solution?

Accepted Answer

It is a strong acid.

Question 5

Which of the following equations correctly represents the dissociation of water?

Accepted Answer

$$H_2O \rightarrow H^+ + OH^-$$

Question 6

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because its molecules form a crystalline structure held together by hydrogen bonds.

Question 7

Which of the following is a consequence of water's high heat of vaporization for living organisms?

Accepted Answer

It enables evaporative cooling, such as sweating in humans.

Question 8

Which of the following best describes a buffer in a biological system?

Accepted Answer

A buffer is a substance that maintains a stable pH by accepting or donating $$H^+$$ ions.

Question 9

Which of the following scenarios best illustrates the importance of hydrogen bonding in water?

Accepted Answer

Water climbing up a plant stem through capillary action.

Question 10

A scientist mixes equal volumes of a solution with pH 4 and a solution with pH 10. What is the expected pH of the resulting mixture, assuming equal buffering capacity and no other reactions?

Accepted Answer

pH 7

Question 11

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

Accepted Answer

The partial charges on water molecules interact with the positive and negative ions of NaCl, separating them.

Question 12

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

Accepted Answer

Water is a good conductor of electricity in its pure form.

Question 13

Which of the following best describes the role of buffers in human blood?

Accepted Answer

Buffers keep the blood pH within a narrow range, typically around 7.4.

Question 14

Which of the following is an example of a hydrogen bond?

Accepted Answer

The attraction between the hydrogen atom of one water molecule and the oxygen atom of another water molecule.

Question 15

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

Accepted Answer

Sweat absorbs heat as it evaporates due to water's high heat of vaporization.

Question 16

Which of the following is the correct formula for calculating pH?

Accepted Answer

$$pH = -\log_{10}[H^+]$$

Question 17

Which of the following best describes the process of neutralization?

Accepted Answer

An acid reacts with a base to form water and a salt.

Question 18

Which of the following is a real-life example of the importance of water's cohesion and adhesion?

Accepted Answer

Water moving up the xylem vessels in plants against gravity.

Question 19

Which of the following best explains why the ocean resists changes in temperature?

Accepted Answer

Water has a high specific heat capacity, allowing it to absorb large amounts of heat with little temperature change.

The Chemical Basis of Life: Study Guide and Key Concepts

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