Question 1

Which of the following statements best describes an element?

Accepted Answer

A substance that cannot be broken down to other substances by chemical reactions.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much will remain after 30 years?

Accepted Answer

$$ 10 	ext{ grams} $$

Question 4

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

Accepted Answer

Ionic bonds between oppositely charged ions

Question 5

What is the main reason that water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons

Question 6

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 7

A PET scan uses radioactive tracers to monitor metabolic activity. Which property of radioactive isotopes makes this possible?

Accepted Answer

They emit energy and particles as they decay

Question 8

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of a pair of valence electrons between two atoms

Question 9

Which type of chemical bond is primarily responsible for holding together the two strands of DNA?

Accepted Answer

Hydrogen bonds

Question 10

If an atom has an atomic number of 7 and a mass number of 15, how many neutrons does it have?

Accepted Answer

$$ 8 $$

Question 11

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have a full valence shell of electrons

Question 12

Which of the following is an example of a trace element required by humans?

Accepted Answer

Iron

Question 13

Which statement best describes chemical equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate

Question 14

Which of the following is a real-world example of an emergent property?

Accepted Answer

Table salt (NaCl) has properties different from sodium and chlorine alone

Question 15

Which of the following best describes van der Waals interactions?

Accepted Answer

Weak attractions between molecules due to temporary local charges

Question 16

Which of the following is true about the energy levels of electrons in an atom?

Accepted Answer

Electrons farther from the nucleus have higher potential energy

Question 17

Which of the following best explains why opiates and endorphins can have similar effects in the brain?

Accepted Answer

They have similar molecular shapes and bind to the same receptors

Question 18

Which of the following is the correct balanced equation for photosynthesis?

Accepted Answer

$$ 6 	ext{CO}_2 + 6 	ext{H}_2	ext{O} ightarrow 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6 	ext{O}_2 $$

Question 19

Which of the following best describes the relationship between atomic number and atomic mass?

Accepted Answer

Atomic number is the number of protons; atomic mass is the sum of protons and neutrons

Question 20

Which of the following is a consequence of the reversibility of weak chemical bonds in biological systems?

Accepted Answer

Molecules can interact temporarily and then separate as needed

The Chemical Context of Life (Campbell Biology, Ch. 2) – Study Notes

Study Guide - Practice Questions