Question 1

Which of the following best explains why sodium (Na) and chlorine (Cl) form an ionic bond to create sodium chloride (NaCl)?

Accepted Answer

Sodium donates an electron to chlorine, resulting in oppositely charged ions that attract each other.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

A patient is diagnosed with an iodine deficiency. Iodine is classified as which type of element in the human body?

Accepted Answer

Trace element

Question 4

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on the atoms.

Question 5

What is the electron configuration for an oxygen atom (atomic number 8) in terms of electrons in the first, second, and third shells?

Accepted Answer

$$2, 6, 0$$

Question 6

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds form between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 7

A gecko can climb smooth walls due to which type of chemical interaction?

Accepted Answer

Van der Waals interactions

Question 8

Which of the following best describes a chemical reaction at equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate.

Question 9

Which of the following is a correct balanced equation for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 10

Which of the following best explains why large biological molecules are often held together by weak bonds?

Accepted Answer

Weak bonds allow for flexibility and reversibility in molecular interactions.

Question 11

If an atom has a full valence shell, what is its chemical behavior?

Accepted Answer

It is chemically inert and does not readily form bonds.

Question 12

Which of the following is a real-life example of a chemical defense mechanism in biology?

Accepted Answer

Red wood ants (Formica rufa) spraying formic acid to deter predators.

Question 13

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation is positively charged, and an anion is negatively charged.

Question 14

Which of the following elements is considered a trace element in the human body?

Accepted Answer

Iron (Fe)

Question 15

Which of the following best explains why water (H$$_2O) is a $$polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

Question 16

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are shared or transferred to form chemical bonds.

Question 17

A person carefully walking on a slippery sidewalk is most analogous to which type of chemical bond?

Accepted Answer

Hydrogen bond

Question 18

Which of the following best describes the emergent properties of compounds?

Accepted Answer

Compounds have new properties that are different from those of their constituent elements.

Question 19

Which of the following best explains why covalent bonds are generally stronger than ionic bonds in aqueous solutions?

Accepted Answer

Water molecules shield ions from each other, weakening ionic bonds.

Question 20

Which of the following is the correct balanced equation for photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O \xrightarrow{	ext{sunlight}} C_6H_{12}O_6$ + 6O_2$$

The Chemical Context of Life (Campbell Biology, Chapter 2)

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