Question 1

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

Accepted Answer

Water's polarity allows it to form hydration shells around Na+ and Cl- ions, stabilizing them in solution.

Question 2

Which property of water is MOST responsible for the ability of insects to walk on its surface?

Accepted Answer

Cohesion due to hydrogen bonding

Question 3

A solution has a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-5}$$ M. What is the pH of this solution?

Accepted Answer

$$pH = 5$$

Question 4

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of valence electrons between atoms.

Question 5

What is the main function of a buffer in biological systems?

Accepted Answer

To maintain a stable pH by accepting or donating H+ ions.

Question 6

Which of the following best describes a hydrophobic substance?

Accepted Answer

A substance that does not interact with water because it is nonpolar.

Question 7

If the concentration of $$[OH^-] in a $$solution is $$1 	imes 10$$^{-8}$$ M at 25°C, what is the concentration of $$[H^+]$$?

Accepted Answer

$$1 	imes 10$$^{-6}$$ M$

Question 8

Which of the following is a trace element essential for life?

Accepted Answer

Iron

Question 9

A buffer system in blood involves carbonic acid ($$H_2CO_3) $$and bicarbonate ($$HCO_3$$^-$$). What happens when a strong acid is added to the blood?

Accepted Answer

Bicarbonate acts as a base and accepts H+ ions, minimizing pH change.

Question 10

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

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity; nonpolar covalent bonds involve equal sharing.

Question 11

Which of the following is the correct order of structural organization in biology from smallest to largest?

Accepted Answer

Atom, molecule, cell, organ

Question 12

Which statement best explains why ice floats on water?

Accepted Answer

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

Question 13

A patient’s blood pH drops from 7.4 to 7.1. What is the effect on enzyme activity in the blood?

Accepted Answer

Enzyme activity decreases because most enzymes function optimally at pH 7.4.

Question 14

Which of the following is true about ionic bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another.

Question 15

Which of the following molecules can act as both an acid and a base in water?

Accepted Answer

H2O

Question 16

A solution has a pH of 3. What is the concentration of hydrogen ions ($$[H^+]) in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-3}$$ M

Question 17

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons determine the chemical reactivity and bonding properties of an atom.

Question 18

Which of the following is NOT a property that contributes to water’s suitability for life on Earth?

Accepted Answer

Ability to dissolve nonpolar substances

Question 19

A scientist adds a strong base to a solution, increasing the $$[OH^-]$$ concentration. What happens to the $$[H^+]$$ concentration?

Accepted Answer

It decreases.

Question 20

Which of the following best explains why trace elements are important for living organisms?

Accepted Answer

They are necessary for the function of certain enzymes and biological processes.

Atoms, Molecules, and Water: Foundations of Biological Chemistry

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