Question 1

Which of the following statements best explains why water is an excellent solvent for ionic compounds such as sodium chloride (NaCl)?

Accepted Answer

Water molecules have partial positive and negative charges that interact with the ions, allowing them to dissolve.

Question 2

A neutral atom of carbon-14 has an atomic number of 6 and a mass number of 14. How many neutrons does it have?

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

Which property of water allows it to moderate temperature changes in organisms and their environments?

Accepted Answer

Water's high specific heat due to hydrogen bonding

Question 4

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electrons between two atoms

Question 5

A sodium atom (Na) has 11 protons and 12 neutrons. What is its mass number?

Accepted Answer

$$11 + 12 = 23$$

Question 6

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because its molecules form a crystalline lattice with more open space.

Question 7

Which of the following is true about valence electrons and chemical bonding?

Accepted Answer

Atoms with unpaired valence electrons tend to form chemical bonds to achieve stability.

Question 8

A molecule of water (H$$_2O) is $$described as polar. What does this mean?

Accepted Answer

The molecule has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom.

Question 9

Which of the following best explains why water has a high surface tension?

Accepted Answer

Hydrogen bonds between water molecules create cohesive forces at the surface.

Question 10

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 11

Which of the following best describes the role of carbon in organic molecules?

Accepted Answer

Carbon can form up to four covalent bonds, allowing for complex and diverse molecular structures.

Question 12

A chlorine atom has 17 protons and 18 neutrons. What is its atomic number and mass number?

Accepted Answer

Atomic number: $$17$$, Mass number: $$17 + 18 = 35$$

Question 13

Which of the following scenarios best illustrates adhesion?

Accepted Answer

Water molecules sticking to the sides of a glass tube, causing the water to climb up the tube

Question 14

Which of the following is a consequence of water's high specific heat for living organisms?

Accepted Answer

Water helps buffer organisms against sudden temperature changes, maintaining stable internal conditions.

Question 15

If an atom has 8 protons, 8 neutrons, and 8 electrons, what is its atomic mass and atomic number?

Accepted Answer

Atomic mass: $$8 + 8 = 16$$, Atomic number: $$8$$

Question 16

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

Accepted Answer

Oil molecules are nonpolar and cannot form hydrogen bonds with water.

Question 17

Which of the following is a real-life example of water's cohesive property?

Accepted Answer

Water moving up a plant stem against gravity

Question 18

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a partially positive hydrogen atom and a partially negative atom (such as oxygen) in another molecule

Question 19

Which of the following statements about the octet rule is correct?

Accepted Answer

Atoms are stable when their outer shell has 8 electrons, except for the first shell, which is stable with 2 electrons.

Question 20

Which of the following best explains why water is less dense as a solid than as a liquid?

Accepted Answer

Hydrogen bonds in ice hold water molecules farther apart in a crystalline lattice.

Atoms, Ions, Molecules, and Water: Foundations of Chemical Evolution in Biology

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