Question 1

Which of the following best explains why water has a high specific heat compared to alcohol, iron, or air?

Accepted Answer

Water molecules form strong hydrogen bonds that require more energy to break.

Question 2

A sodium atom (Na) loses one electron to become Na⁺. What type of ion is this, and what is its charge?

Accepted Answer

Cation; positive charge

Question 3

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally due to a difference in electronegativity between atoms.

Question 4

Given the electronegativity values: Oxygen = 3.5, Hydrogen = 2.1, what is the difference in electronegativity, and what type of bond forms between them?

Accepted Answer

$$3.5 - 2.1 = 1.4$$, polar covalent bond

Question 5

Why does ice float on liquid water, and why is this property important for aquatic life in winter?

Accepted Answer

Ice is less dense than liquid water due to the arrangement of hydrogen bonds, allowing it to float and insulate the water below, protecting aquatic life.

Question 6

Which property of water allows it to dissolve many substances, such as salt and sugar?

Accepted Answer

Water's polarity allows it to surround and separate charged or polar molecules, making it an excellent solvent.

Question 7

A demonstration shows a spoon sinking in oil and alcohol, but floating in water. Which property of water is being demonstrated?

Accepted Answer

Cohesion, due to hydrogen bonding between water molecules

Question 8

Which of the following best describes capillary action in plants?

Accepted Answer

It is the result of both cohesion and adhesion, allowing water to move from roots to leaves.

Question 9

If the difference in electronegativity between two atoms is greater than $$1.7$$, what type of bond is most likely to form?

Accepted Answer

Ionic bond

Question 10

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds are much weaker than covalent bonds, being only about $$\frac{1}{20} as $$strong.

Question 11

Why does sweating help cool the human body, based on water's properties?

Accepted Answer

Evaporation of sweat requires heat energy (high heat of vaporization), which is taken from the body, cooling it.

Question 12

Which of the following best explains why salt (NaCl) dissolves easily in water but not in oil?

Accepted Answer

Water is polar and can surround the charged ions of salt, while oil is non-polar and cannot.

Question 13

Which of the following is an example of adhesion?

Accepted Answer

Water sticking to the surface of glass

Question 14

A meniscus forms in a graduated cylinder when water is added. What causes this phenomenon?

Accepted Answer

Adhesion between water molecules and the glass

Question 15

Which of the following best describes the role of water in chemical reactions in living organisms?

Accepted Answer

Water acts as a solvent, allowing chemical reactions to occur in solution.

Question 16

Which of the following is a real-life example of cohesion in water?

Accepted Answer

A basilisk lizard running across the surface of a pond

Question 17

If a pond freezes at the top but remains liquid below, which property of water is responsible for this phenomenon?

Accepted Answer

Ice is less dense than liquid water, so it floats and insulates the water below.

Question 18

Which of the following best explains why water can travel up a plant stem against gravity?

Accepted Answer

Capillary action, which is due to both cohesion and adhesion

Question 19

Which of the following statements about covalent and ionic bonds in living organisms is correct?

Accepted Answer

Covalent bonds are stronger than ionic bonds in living organisms.

Question 20

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between like molecules; adhesion is the attraction between different substances.

Chemical Bonds and Properties of Water

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