Question 1

Which of the following statements best explains why water is considered the 'solvent of life'?

Accepted Answer

Water's polarity enables it to surround and dissolve ionic and polar molecules, forming aqueous solutions.

Question 2

A patient is given a radioactive isotope as a tracer for a diagnostic test. Which property of isotopes makes this possible?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons, allowing some to be radioactive and traceable.

Question 3

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

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms, while ionic bonds involve the transfer of electrons from one atom to another.

Question 4

Which equation correctly represents the balanced chemical reaction for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 5

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice create a lattice that spaces molecules farther apart, making ice less dense than liquid water.

Question 6

A solution has a pH of 4. How does its hydrogen ion concentration $$[H^+]$$ compare to a solution with a pH of 7?

Accepted Answer

It is 1,000 times higher.

Question 7

Which of the following best explains why sweating cools the human body?

Accepted Answer

Sweat absorbs heat as it evaporates, due to the breaking of hydrogen bonds, resulting in evaporative cooling.

Question 8

Which of the following is a trace element essential for human health and often added to drinking water to prevent disease?

Accepted Answer

Fluoride

Question 9

A molecule of methane ($$CH_4) is $$held together by which type of bond?

Accepted Answer

Nonpolar covalent bonds

Question 10

Which property of water is most directly responsible for the movement of water from the roots to the leaves in plants?

Accepted Answer

Cohesion due to hydrogen bonding

Question 11

If a solution has a $$[H^+] of$$ $$1 	imes 10$$^{-9}$$ M, what is its pH?

Accepted Answer

$$pH = 9$$

Question 12

Which of the following best describes a buffer in biological systems?

Accepted Answer

A buffer minimizes changes in pH by accepting or donating hydrogen ions.

Question 13

Which of the following is true about the atomic number of an element?

Accepted Answer

It is the number of protons in the nucleus.

Question 14

Which scenario best illustrates the concept of adhesion?

Accepted Answer

Water molecules sticking to the walls of a plant's xylem vessels.

Question 15

Which of the following best explains why the presence of water is important in the search for extraterrestrial life?

Accepted Answer

Water's unique properties support the complex chemistry required for life.

Question 16

Which of the following best describes a chemical reaction?

Accepted Answer

A process that rearranges chemical bonds to convert reactants into products.

Question 17

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

Accepted Answer

Hydrogen bonds form between the hydrogen atom of one molecule and an electronegative atom of another molecule.

Question 18

A scientist adds sodium chloride ($$NaCl) to $$water. What happens at the molecular level?

Accepted Answer

The $$Na^+$$ and $$Cl^-$$ ions are surrounded by water molecules due to water's polarity.

Question 19

Which of the following best explains why life-supporting properties of water are considered 'emergent properties'?

Accepted Answer

They result from the collective interactions of water molecules, such as hydrogen bonding, that are not present in individual molecules.

Chapter 2: The Chemical Basis of Life – Elements, Atoms, and Compounds

Study Guide - Practice Questions