$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which of the following best explains why table salt (NaCl) is considered to have emergent properties?

Accepted Answer

NaCl is edible and safe, while its constituent elements, sodium and chlorine, are both dangerous in their pure forms.

Question 2

Which four elements make up approximately 96% of the human body’s mass?

Accepted Answer

Oxygen, carbon, hydrogen, nitrogen

Question 3

A radioactive isotope is used as a tracer in medical imaging. Which property makes this possible?

Accepted Answer

Radioactive isotopes emit detectable energy as they decay.

Question 4

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

Accepted Answer

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Question 5

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

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 6

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart, making ice less dense than liquid water.

Question 7

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by accepting or donating hydrogen ions.

Question 8

What is the main reason water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water is a polar molecule, allowing it to surround and separate ions and polar molecules.

Question 9

Which of the following is a real-world consequence of ocean acidification caused by increased atmospheric $$CO_2$$?

Accepted Answer

Decreased carbonate ion concentration reduces the rate of coral calcification.

Question 10

A neutral atom of carbon-14 has how many protons, neutrons, and electrons?

Accepted Answer

6 protons, 8 neutrons, 6 electrons

Question 11

Which property of water allows a water strider to walk on the surface of a pond?

Accepted Answer

Surface tension due to cohesion among water molecules

Question 12

Which of the following best describes a chemical reaction?

Accepted Answer

A process that breaks and forms chemical bonds, rearranging atoms into new substances

Question 13

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 14

Which of the following is an example of a polar covalent bond?

Accepted Answer

The bonds between oxygen and hydrogen in a water molecule

Question 15

If a solution has a pH of 9, which of the following statements is true?

Accepted Answer

The solution is basic and has a lower $$[H^+]$$ than pure water.

Question 16

Which of the following best explains why water has a high specific heat?

Accepted Answer

Hydrogen bonds between water molecules absorb heat when they break and release heat when they form.

Question 17

Which of the following is a trace element required by humans and often added to drinking water to prevent disease?

Accepted Answer

Fluorine (as fluoride)

Question 18

Which of the following best describes the process of evaporative cooling?

Accepted Answer

As water evaporates, the surface of the remaining liquid cools down because the molecules with the most energy leave first.

Question 19

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

Accepted Answer

It is equal to the number of protons in the nucleus.

Question 20

Which of the following best explains why scientists search for water when looking for extraterrestrial life?

Accepted Answer

Water’s unique properties support life as we know it, making it essential for biological processes.

Chapter 2: The Chemical Basis of Life – Study Notes

Study Guide - Practice Questions