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

What is the atomic number of an element?

Accepted Answer

The number of protons in its nucleus

Question 4

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 5

Which type of bond involves the sharing of a pair of valence electrons by two atoms?

Accepted Answer

Covalent bond

Question 6

What is the main difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

In a polar covalent bond, electrons are shared unequally; in a nonpolar covalent bond, electrons are shared equally.

Question 7

Which of the following best describes a cation?

Accepted Answer

An atom that has lost one or more electrons and has a positive charge

Question 8

Which of the following is true about chemical equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate, and the concentrations of reactants and products remain constant.

Question 9

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, resulting in unequal sharing of electrons.

Question 10

Which of the following weak interactions is responsible for the ability of a gecko to climb smooth surfaces?

Accepted Answer

Van der Waals interactions

Question 11

A radioactive isotope of carbon, $$^{14}C$$, has 6 protons. How many neutrons does it have?

Accepted Answer

$$8$$

Question 12

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

Accepted Answer

Atomic mass is approximately equal to the mass number, which is the sum of protons and neutrons.

Question 13

Which of the following statements about electron shells is correct?

Accepted Answer

Electrons in the outermost shell have the highest potential energy.

Question 14

Which of the following is a real-life example of a chemical reaction important for life?

Accepted Answer

Photosynthesis: $$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 15

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

Accepted Answer

They have full valence shells.

Question 16

A molecule of methane ($$CH_4) $$has what type of bonds between carbon and hydrogen?

Accepted Answer

Nonpolar covalent bonds

Question 17

Which of the following best describes a hydrogen bond?

Accepted Answer

An attraction between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom

Question 18

If an atom has an atomic number of $$11$$ and a mass number of $$23$$, how many neutrons does it have?

Accepted Answer

$$12$$

Question 19

Which of the following is true about the formation of an ionic bond?

Accepted Answer

It involves the transfer of electrons from one atom to another, resulting in oppositely charged ions that attract each other.

Question 20

Which of the following best explains the importance of molecular shape in biology?

Accepted Answer

Molecular shape determines how biological molecules recognize and respond to one another.

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

Study Guide - Practice Questions