Question 1

Which of the following best describes an isotope?

Accepted Answer

An atom with the same number of protons but a different number of neutrons.

Question 2

Which equation correctly represents the calculation of pH?

Accepted Answer

$$\mathrm{pH} = -\log_{10}[\mathrm{H}^+]$$

Question 3

A patient’s blood pH drops from 7.4 to 7.1. Which of the following best explains what has happened?

Accepted Answer

The concentration of $$\mathrm{H}^+$$ ions has increased.

Question 4

Which property of water allows insects to walk on its surface?

Accepted Answer

Cohesion due to hydrogen bonding

Question 5

Which of the following is a real-life example of a buffer system in the human body?

Accepted Answer

The carbonic acid-bicarbonate system maintaining blood pH

Question 6

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 7

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because its molecules are more spread out.

Question 8

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

Accepted Answer

Water molecules are polar and can surround and separate ions.

Question 9

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$5$$

Question 10

Which of the following statements about free radicals is correct?

Accepted Answer

Free radicals are unstable and can damage cellular molecules.

Question 11

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Question 12

Which property of water helps moderate Earth's climate by absorbing heat energy?

Accepted Answer

High specific heat

Question 13

Which of the following is a consequence of water’s high heat of vaporization for living organisms?

Accepted Answer

It enables evaporative cooling, such as sweating in humans.

Question 14

A molecule of sodium chloride (NaCl) dissolves in water. What type of bond is broken in this process?

Accepted Answer

Ionic bond

Question 15

Which of the following best explains why buffers are important in biological systems?

Accepted Answer

They maintain a stable pH by accepting or donating $$\mathrm{H}^+$$ ions.

Question 16

Which of the following is an example of adhesion in water?

Accepted Answer

Water molecules sticking to the walls of plant vessels

Question 17

Which of the following best describes the role of electron shells in atoms?

Accepted Answer

They determine the chemical reactivity of an atom.

Question 18

Which of the following is a real-world consequence of the density difference between ice and liquid water?

Accepted Answer

Ice floats, insulating aquatic life during winter.

Question 19

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

Accepted Answer

Water’s polar molecules surround and separate the Na+ and Cl- ions.

Question 20

Which of the following is a correct statement about hydrogen bonds?

Accepted Answer

They form between a hydrogen atom and an electronegative atom like oxygen.

Atoms, Molecules, and Life: Study Notes

Study Guide - Practice Questions