Question 1

Which of the following statements best explains why water is considered the 'solvent of life'?

Accepted Answer

Water's polarity allows it to surround and dissolve ionic and polar molecules, forming aqueous solutions.

Question 2

A radioactive isotope of nitrogen has 7 protons and 9 neutrons. What are its atomic number and mass number?

Accepted Answer

Atomic number: 7, Mass number: 16

Question 3

Which property of water is primarily responsible for the phenomenon of surface tension?

Accepted Answer

Cohesion due to hydrogen bonding between water molecules

Question 4

Why do ice cubes float in a glass of water?

Accepted Answer

Hydrogen bonds in ice cause the molecules to be less densely packed than in liquid water.

Question 5

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from one atom to another, resulting in attraction between oppositely charged ions.

Question 6

A solution has a pH of 4. Compared to a solution with pH 7, how does its hydrogen ion concentration $$[H^+]$$ compare?

Accepted Answer

It is 100 times higher.

Question 7

Which of the following is a trace element that is added to municipal water supplies to help prevent tooth decay?

Accepted Answer

Fluoride

Question 8

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 9

Which of the following is true about isotopes of an element?

Accepted Answer

They have the same number of protons but different numbers of neutrons.

Question 10

A scientist uses a radioactive isotope as a tracer to follow the movement of a substance in a living organism. What property of radioactive isotopes makes this possible?

Accepted Answer

They emit detectable radiation as they decay.

Question 11

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on the atoms.

Question 12

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

Accepted Answer

Water is a nonpolar solvent.

Question 13

Which of the following best explains why the presence of water is considered essential in the search for extraterrestrial life?

Accepted Answer

Water's unique properties make it an ideal medium for the chemical reactions necessary for life.

Question 14

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

Accepted Answer

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

Question 15

Which of the following is the correct formula for calculating the mass number of an atom?

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 16

Which of the following scenarios best illustrates a chemical reaction?

Accepted Answer

Hydrogen and oxygen gases combining to form water: $$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 17

Which of the following statements about the composition of the human body is correct?

Accepted Answer

Oxygen, carbon, hydrogen, and nitrogen make up about 96% of the human body.

Question 18

Which of the following best explains why sodium chloride (NaCl) forms a crystal lattice structure?

Accepted Answer

Attraction between oppositely charged ions (Na$$^+$$ and Cl$$^-) $$forms a repeating pattern.

Question 19

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between molecules of the same substance; adhesion is the attraction between different substances.

Question 20

Which of the following best explains why water is able to moderate Earth's climate?

Accepted Answer

Water's high specific heat allows it to absorb and release large amounts of heat with little temperature change.

Elements, Atoms, and Compounds: Foundations of Chemistry in Biology

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