Question 1

Which of the following best explains why sodium (Na) and chlorine (Cl) combine to form sodium chloride (NaCl) with properties very different from the original elements?

Accepted Answer

NaCl is a compound formed by an ionic bond, resulting in emergent properties different from sodium and chlorine.

Question 2

A patient is diagnosed with goiter due to a deficiency of an essential trace element. Which element is most likely deficient, and what is its biological role?

Accepted Answer

Iodine (I); required for normal thyroid gland activity.

Question 3

Which process describes how sunflowers are used to clean up soils contaminated with heavy metals such as lead and zinc?

Accepted Answer

Phytoremediation

Question 4

Given a sodium atom with atomic number 11 and mass number 23, how many neutrons does it have? Use the formula $$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}.$$

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 5

Which statement correctly describes the difference between atomic number and mass number?

Accepted Answer

Atomic number is the number of protons; mass number is the sum of protons and neutrons.

Question 6

Carbon-12, carbon-13, and carbon-14 are isotopes. What do all isotopes of carbon have in common?

Accepted Answer

They have the same number of protons.

Question 7

Which of the following best describes what happens when an electron absorbs energy?

Accepted Answer

It moves to a higher energy shell farther from the nucleus.

Question 8

Why is water considered a polar molecule?

Accepted Answer

Because oxygen is more electronegative, creating partial charges on the molecule.

Question 9

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 10

What is the main reason ice floats on liquid water?

Accepted Answer

Hydrogen bonds in ice are more ordered, making ice less dense than liquid water.

Question 11

Which property of water allows a spider to walk on its surface without sinking?

Accepted Answer

Surface tension due to cohesion among water molecules

Question 12

A solution has a pH of 5. Which of the following statements is true?

Accepted Answer

The solution is acidic and has a high H+ concentration.

Question 13

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

Accepted Answer

Buffers minimize changes in the concentrations of H+ and OH- in a solution.

Question 14

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

Accepted Answer

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

Question 15

Why are van der Waals interactions important in biological systems, despite being individually weak?

Accepted Answer

Their cumulative effect can stabilize large biological molecules and enable phenomena like geckos walking on walls.

Question 16

Which of the following best explains why oil does not dissolve in water?

Accepted Answer

Oil is nonpolar and hydrophobic, so it does not interact favorably with polar water molecules.

Question 17

A plant transports water from its roots to its leaves. Which combination of water properties is most directly responsible for this process?

Accepted Answer

Cohesion and adhesion due to hydrogen bonding

Question 18

Which equation correctly represents the process of photosynthesis?

Accepted Answer

$$6 	ext{CO}_2 + 6 	ext{H}_2	ext{O} + 	ext{sunlight} ightarrow 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6 	ext{O}_2$$

Question 19

Which of the following best describes an aqueous solution?

Accepted Answer

A solution in which water is the solvent.

Question 20

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

Accepted Answer

Acids increase the H+ concentration, while bases decrease it.

Chapter 2: The Chemical Context of Life – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards