Question 1

Which of the following best explains why table salt (NaCl) is an example of emergent properties?

Accepted Answer

Table salt is a compound that has properties different from those of its constituent elements, sodium (a reactive metal) and chlorine (a poisonous gas).

Question 2

A nitrogen atom has 7 protons and its most common isotope has 7 neutrons. What is the atomic number and mass number of a radioactive isotope of nitrogen with 9 neutrons?

Accepted Answer

Atomic number = 7, Mass number = 16

Question 3

Which of the following statements about radioactive isotopes is TRUE?

Accepted Answer

Radioactive isotopes can be used as tracers to monitor the fate of atoms in living organisms.

Question 4

How many covalent bonds can a carbon atom form, based on its electron distribution?

Accepted Answer

Four

Question 5

Which of the following best describes what holds together the ions in a crystal of table salt (NaCl)?

Accepted Answer

Attraction between oppositely charged ions (ionic bond)

Question 6

Why are the bonds in a water molecule considered polar covalent bonds?

Accepted Answer

Oxygen is more electronegative than hydrogen, so electrons are pulled closer to oxygen, creating a partial negative charge on oxygen and partial positive charges on hydrogens.

Question 7

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

Accepted Answer

Cohesion due to hydrogen bonding, resulting in high surface tension

Question 8

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 9

Which of the following best explains why water is called the 'universal solvent'?

Accepted Answer

Water’s polarity allows it to dissolve many polar and ionic substances by surrounding them with water molecules.

Question 10

Compared to a basic solution at pH 9, the same volume of an acidic solution at pH 4 has how many times more $$H^+$$ ions?

Accepted Answer

$$100,000$$

Question 11

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

Accepted Answer

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

Question 12

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

Accepted Answer

Buffers minimize changes in pH by accepting or donating $$H^+$$ ions.

Question 13

What is the main chemical process by which rising atmospheric $$CO_2$$ harms coral reefs?

Accepted Answer

$$CO_2$$ dissolves in seawater, forming carbonic acid, which lowers pH and reduces carbonate ion concentration needed for coral skeletons.

Question 14

A serving of cereal contains $$18\ mg of $$iron, and the recommended upper intake level is $$45\ mg. $$How many bowls can you eat before exceeding the upper limit?

Accepted Answer

3

Question 15

Which of the following is NOT a life-supporting property of water?

Accepted Answer

Water is a nonpolar solvent.

Question 16

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 necessary for life.

Question 17

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 18

Which of the following is a trace element commonly added to water to prevent disease?

Accepted Answer

Fluoride

Question 19

Which of the following is TRUE about chemical reactions?

Accepted Answer

Chemical reactions rearrange atoms to form new substances without creating or destroying matter.

Question 20

Which of the following best explains why blood is classified as an aqueous solution?

Accepted Answer

Blood contains many dissolved substances in water, making it a uniform mixture.

Chapter 2: The Chemical Basis of Life – Study Notes

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