Question 1

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

Accepted Answer

Water is polar, so its partially positive and negative charges can surround and stabilize ions in solution.

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

$$8$$

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

If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its atomic mass?

Accepted Answer

$$23$$

Question 6

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice create a lattice that is less dense than liquid water.

Question 7

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 8

A sodium atom (Na) loses one electron to become a sodium ion (Na⁺). What happens to its charge and electron configuration?

Accepted Answer

It becomes positively charged and has a full outer shell.

Question 9

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

Accepted Answer

Hydrogen bonds form between water molecules, holding them together.

Question 10

Which statement about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical reactivity of an atom.

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

Nonpolar covalent bond

Question 12

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 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

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

Accepted Answer

Carbon can form four covalent bonds due to its four valence electrons.

Question 15

Which of the following is the correct formula for calculating the mass number of an atom?

Accepted Answer

$$	ext{Mass number} = 	ext{protons} + 	ext{neutrons}$$

Question 16

Which of the following scenarios best illustrates the property of adhesion in water?

Accepted Answer

Water molecules sticking to the sides of a glass tube, causing a meniscus

Question 17

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

Accepted Answer

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

Question 18

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally, resulting in partial charges on atoms

Question 19

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

Accepted Answer

Water forming droplets on a leaf after rain

Question 20

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds form between the hydrogen atom of one water molecule and the oxygen atom of another water molecule.

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

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