Question 1

Which of the following best explains why noble gases are generally unreactive in chemical reactions?

Accepted Answer

They have complete valence shells, making them energetically stable.

Question 2

A sodium atom (Na) reacts with a chlorine atom (Cl) to form sodium chloride (NaCl). What type of bond is formed, and what happens to the electrons?

Accepted Answer

An ionic bond is formed by transferring an electron from Na to Cl.

Question 3

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity is the tendency of an atom to attract shared electrons in a bond.

Question 4

Given the electronegativity difference between two atoms is 2.5, what type of bond will most likely form between them?

Accepted Answer

Ionic bond

Question 5

Which property of water allows it to moderate Earth's temperature and why?

Accepted Answer

High specific heat capacity, because it resists temperature changes.

Question 6

Why does ice float on liquid water, and what would be the consequence if it did not?

Accepted Answer

Ice is less dense than liquid water due to stable hydrogen bonds, so it floats; if it did not, aquatic life would not survive in winter.

Question 7

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a partially positive hydrogen atom and a more electronegative atom.

Question 8

A molecule of water (H$$_2O) is $$held together by which type of bond, and what property does this give water?

Accepted Answer

Covalent bonds; water is a polar molecule.

Question 9

Which of the following scenarios best illustrates the concept of cohesion in water?

Accepted Answer

Water droplets forming beads on a waxed car hood due to water molecules sticking together.

Question 10

A patient is given an intravenous (IV) solution that is hydrophilic. What does this mean about the solution's interaction with water?

Accepted Answer

It will dissolve in water because it is polar or charged.

Question 11

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

Accepted Answer

Water molecules surround the Na$$^+$$ and Cl$$^-$$ ions, forming hydration shells due to their polarity.

Question 12

Which of the following is a direct biological consequence of water's high specific heat capacity?

Accepted Answer

Organisms maintain relatively stable internal temperatures despite external fluctuations.

Question 13

If a molecule has a large difference in electronegativity between its atoms (greater than 2), what is the most likely result?

Accepted Answer

The molecule will form an ionic bond.

Question 14

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

Accepted Answer

Oil is nonpolar and hydrophobic, so it cannot interact with polar water molecules.

Question 15

Which emergent property of water is most important for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesive behavior

Question 16

A double covalent bond involves the sharing of how many electrons between two atoms?

Accepted Answer

Four electrons

Question 17

Which of the following is NOT a major element found in the human body according to Table 2.1?

Accepted Answer

Boron

Question 18

Which property of water is responsible for its ability to dissolve a wide variety of substances?

Accepted Answer

Its polarity and ability to form hydrogen bonds

Question 19

A scientist observes that water climbs up a thin glass tube without any external force applied. Which property of water is primarily responsible for this phenomenon?

Accepted Answer

Adhesion and cohesion, resulting in capillary action

Question 20

Which of the following best explains why the structure of DNA depends on hydrogen bonds?

Accepted Answer

Hydrogen bonds form between complementary bases, stabilizing the double helix.

Valence Electrons, Chemical Bonds, and the Properties of Water

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