Question 1

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element is a substance that cannot be broken down into other substances by chemical means, while a compound consists of two or more elements chemically combined in a fixed ratio.

Question 2

A neutral atom of carbon has an atomic number of 6 and a mass number of 14. How many neutrons does it have?

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

Which of the following best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water is polar, so its partial positive and negative charges can surround and separate ions.

Question 4

If the pH of a solution changes from 5 to 2, how does the concentration of hydrogen ions $$[H^+]$$ change?

Accepted Answer

It increases by $$10^{(5-2)}$$ = $$10^3 = 1000$ times.

Question 5

Which of the following is a property of water that results directly from hydrogen bonding?

Accepted Answer

High specific heat capacity

Question 6

A sodium atom (Na) has 11 protons and 12 neutrons. What is its mass number, and what is its atomic number?

Accepted Answer

Mass number: $$11 + 12 = 23$$; Atomic number: $$11$$

Question 7

Which of the following best distinguishes a covalent bond from an ionic bond?

Accepted Answer

A covalent bond involves the sharing of electrons, while an ionic bond involves the transfer of electrons.

Question 8

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 9

A solution is made by dissolving table salt (NaCl) in water. In this scenario, which is the solute and which is the solvent?

Accepted Answer

NaCl is the solute; water is the solvent.

Question 10

Which of the following substances is most likely to be hydrophobic?

Accepted Answer

A long hydrocarbon chain, such as oil

Question 11

When water dissociates, which ions are produced?

Accepted Answer

Hydronium ($$H_3O^+) $$and hydroxide ($$OH^-) $$ions

Question 12

Which of the following best describes the function of a buffer in biological systems?

Accepted Answer

A buffer minimizes changes in pH by accepting or donating $$H^+$$ ions.

Question 13

Which of the following best illustrates the concept of adhesion?

Accepted Answer

Water droplets sticking to the surface of a leaf

Question 14

A magnesium atom has an atomic number of 12. How many electrons are in its outer (valence) shell?

Accepted Answer

2

Question 15

Which of the following is a real-life example of water's high heat of vaporization being biologically important?

Accepted Answer

Humans sweating to cool their bodies during exercise

Question 16

If you know the atomic number and the mass number of an atom, how can you determine the number of neutrons?

Accepted Answer

Number of neutrons = mass number $$-$$ atomic number

Question 17

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

Accepted Answer

Hydrogen bonds in ice hold water molecules farther apart, making ice less dense than liquid water.

Question 18

Which of the following is a correct comparison between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between water molecules; adhesion is the attraction between water molecules and other substances.

Question 19

Which of the following best describes an ion?

Accepted Answer

An atom or molecule with a net electrical charge due to the loss or gain of electrons

Question 20

A patient is experiencing acidosis (blood pH below 7.35). Which of the following best explains how a buffer in the blood helps restore normal pH?

Accepted Answer

The buffer accepts excess $$H^+$$ ions, reducing their concentration and raising the pH.

Chapter 2: Chemistry Study Guide – General Biology Guidance

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