Question 1

Which of the following statements best explains why water has a high surface tension compared to most other liquids?

Accepted Answer

Hydrogen bonding between water molecules creates a cohesive force at the surface.

Question 2

A neutral atom of carbon has an atomic number of 6 and an atomic mass of 12. How many neutrons does it have?

Accepted Answer

6

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 4

What type of bond is formed when two atoms share a pair of electrons equally?

Accepted Answer

Nonpolar covalent bond

Question 5

Which property of water allows it to moderate temperature changes in organisms and environments?

Accepted Answer

High specific heat

Question 6

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$1 	imes 10$$^{-4}$$ M

Question 7

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

Accepted Answer

A substance that prevents large changes in pH by accepting or donating H$$^+$$ ions.

Question 8

Which of the following is a real-life example of an ionic compound?

Accepted Answer

Table salt (NaCl)

Question 9

If a molecule is described as hydrophobic, what does this mean about its interaction with water?

Accepted Answer

It does not have an affinity for water and tends to clump together in aqueous solutions.

Question 10

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice has a lower density than liquid water because water expands when it freezes.

Question 11

A sodium atom (Na) has 11 protons and 11 electrons. If it loses one electron, what is the resulting charge and what is this particle called?

Accepted Answer

Charge of +1, called a cation

Question 12

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally, resulting in partial charges on the atoms.

Question 13

What is the molarity of a solution containing 2 moles of NaCl dissolved in 1 liter of water?

Accepted Answer

2 M

Question 14

Which of the following statements about acids and bases is correct?

Accepted Answer

An acid increases the concentration of H$$^+$$ ions in a solution.

Question 15

Which of the following best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water molecules are polar and can surround and separate charged or polar molecules.

Question 16

A molecule of oxygen gas (O$$_2) is $$held together by which type of bond?

Accepted Answer

Double covalent bond

Question 17

If the pH of a solution changes from 7 to 5, how does the hydrogen ion concentration change?

Accepted Answer

It increases by a factor of 100.

Question 18

Which of the following is a function of weak hydrogen bonds in biological systems?

Accepted Answer

They help stabilize the three-dimensional shape of large molecules.

Question 19

Which of the following best describes the relationship between atoms, molecules, and compounds?

Accepted Answer

Molecules are made of atoms, and compounds are molecules composed of two or more different elements.

Question 20

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

Accepted Answer

They maintain a constant pH by accepting or donating H$$^+$$ ions as needed.

Atoms, Molecules, and Life: Foundations of Biological Chemistry

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