Q: Which of the following equations correctly represents the chemical reaction for the formation of water from hydrogen and oxygen?

$$2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$$

Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[\text{H}^+] in $$the solution?

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

Question 1

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

Accepted Answer

NaCl forms a crystal lattice structure that is not present in either sodium or chlorine alone.

Question 2

A radioactive isotope of carbon, carbon-14, is used in PET scans to monitor metabolic activity in the brain. What makes carbon-14 different from carbon-12?

Accepted Answer

Carbon-14 has more neutrons than carbon-12.

Question 3

Which of the following equations correctly represents the chemical reaction for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2	ext{H}_2 + 	ext{O}_2 ightarrow 2	ext{H}_2	ext{O}$$

Question 4

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds hold water molecules farther apart in a crystalline structure.

Question 5

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

Accepted Answer

Cohesion, which leads to high surface tension.

Question 6

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

Accepted Answer

A buffer minimizes changes in pH by accepting or donating H$$^+$$ ions.

Question 7

What is the main reason water is called the 'solvent of life'?

Accepted Answer

Water’s polarity allows it to dissolve many ionic and polar substances.

Question 8

Which of the following statements about chemical bonds is correct?

Accepted Answer

Hydrogen bonds are weak attractions between a hydrogen atom and an electronegative atom.

Question 9

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

Accepted Answer

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

Question 10

Which of the following best explains why rising atmospheric CO$$_2$$ levels threaten coral reefs?

Accepted Answer

CO$$_2$$ dissolves in seawater, forming carbonic acid, which lowers pH and reduces carbonate ion concentration needed for calcification.

Question 11

Which of the following is a trace element essential for human health and commonly added to drinking water to prevent tooth decay?

Accepted Answer

Fluoride

Question 12

Which of the following best describes the difference between a molecule of oxygen (O$$_2) $$and a molecule of water (H$$_2O$$)?

Accepted Answer

O$$_2 is a $$nonpolar molecule, while H$$_2O is a $$polar molecule due to unequal sharing of electrons.

Question 13

Which of the following is true about isotopes?

Accepted Answer

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

Question 14

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

Accepted Answer

Electrons in the outermost shell (valence electrons) determine how atoms interact and bond.

Question 15

A scientist adds hydrochloric acid (HCl) to a beaker of pure water. What happens to the pH of the solution?

Accepted Answer

The pH decreases because HCl releases H$$^+$$ ions, making the solution more acidic.

Question 16

Which of the following is an example of a chemical reaction?

Accepted Answer

Combining hydrogen and oxygen to form water: $$2	ext{H}_2 + 	ext{O}_2 ightarrow 2	ext{H}_2	ext{O}$$

Question 17

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

Accepted Answer

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

Question 18

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

Accepted Answer

As water evaporates, the molecules with the highest energy leave, lowering the temperature of the remaining liquid.

Question 19

Which of the following is NOT a property of water that supports life on Earth?

Accepted Answer

Water is nonpolar and does not form hydrogen bonds.

Chapter 2: The Chemical Basis of Life – Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards