Question 1

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

Accepted Answer

NaCl is a compound, and compounds have emergent properties different from their constituent elements.

Question 2

A patient is diagnosed with goiter due to a deficiency of a 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 the use of sunflowers to remove heavy metals from contaminated soils, and what is the ecological significance of this process?

Accepted Answer

Phytoremediation; it detoxifies polluted environments.

Question 4

Given a sodium atom with atomic number 11 and mass number 23, calculate the number of neutrons in the atom. Use the formula $$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}.$$

Accepted Answer

$$23 - 11 = 12$$ neutrons

Question 5

Which statement best 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 of carbon. Which of the following is true about these isotopes?

Accepted Answer

They have the same number of protons but different numbers of neutrons.

Question 7

A radioactive isotope is used in a PET scan to detect cancerous tissue. What property of radioactive isotopes makes them useful for this purpose?

Accepted Answer

They spontaneously decay, emitting particles and energy that can be detected.

Question 8

Which of the following best describes the movement of electrons between energy shells in an atom?

Accepted Answer

Electrons can move to higher shells by absorbing energy and to lower shells by releasing energy.

Question 9

Which type of chemical bond involves the sharing of electron pairs between atoms, and what is a molecule formed by this bond called?

Accepted Answer

Covalent bond; molecule

Question 10

What is the main difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity; nonpolar covalent bonds involve equal sharing.

Question 11

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

Accepted Answer

Oxygen is more electronegative than hydrogen, resulting in an unequal sharing of electrons.

Question 12

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 13

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

Accepted Answer

Surface tension due to cohesion among water molecules

Question 14

Why does ice float on liquid water, and what would happen if ice sank?

Accepted Answer

Ice is less dense due to ordered hydrogen bonds; if it sank, all bodies of water would eventually freeze solid.

Question 15

A solution is made by dissolving salt in water. In this solution, what is the solvent and what is the solute?

Accepted Answer

Water is the solvent; salt is the solute.

Question 16

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

Accepted Answer

Vegetable oil

Question 17

A buffer is added to a solution to maintain a stable pH. How does a buffer work?

Accepted Answer

It minimizes changes in H$$^+$$ and OH$$^-$$ concentrations by accepting or donating hydrogen ions as needed.

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 van der Waals interactions and their biological significance?

Accepted Answer

They are weak interactions that, in large numbers, can provide significant adhesion, as seen in gecko feet.

Chapter 2: The Chemical Context of Life – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards