Question 1

Which of the following statements best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water molecules are polar, so their partial positive and negative charges can surround and separate ions.

Question 2

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

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

Which property of water allows it to moderate temperature within living organisms and 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 electron pairs between atoms

Question 5

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds hold water molecules further apart in the solid state

Question 6

Which of the following is true about isotopes of an element?

Accepted Answer

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

Question 7

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

Accepted Answer

$$11 + 12 = 23$$

Question 8

Which of the following best explains why water molecules are cohesive?

Accepted Answer

Hydrogen bonds form between water molecules, holding them together

Question 9

Which statement about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical bonding properties of an atom

Question 10

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

Accepted Answer

Water molecules sticking to the sides of a glass tube, allowing water to rise against gravity

Question 11

A molecule of methane ($$CH_4) is $$formed when carbon shares electrons with four hydrogen atoms. What type of bond is formed between carbon and hydrogen?

Accepted Answer

Covalent bond

Question 12

Which of the following best describes a polar covalent bond?

Accepted Answer

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

Question 13

Which of the following is a consequence of water's high surface tension?

Accepted Answer

Small insects can walk on the surface of water without sinking

Question 14

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic number and mass number?

Accepted Answer

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

Question 15

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 16

Which of the following is a correct statement about the octet rule?

Accepted Answer

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

Question 17

Which of the following best describes the difference between hydrophilic and hydrophobic substances?

Accepted Answer

Hydrophilic substances dissolve in water, while hydrophobic substances do not

Question 18

Which of the following is a direct result of hydrogen bonding between water molecules?

Accepted Answer

Water has a high specific heat and high surface tension

Question 19

A chlorine atom has 17 protons and 18 neutrons. What is the atomic mass of this atom?

Accepted Answer

$$17 + 18 = 35$$

Question 20

Which of the following best explains why carbon is able to form large, complex molecules?

Accepted Answer

Carbon has four valence electrons, allowing it to form up to four strong covalent bonds

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

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