Question 1

Which of the following best describes a compound?

Accepted Answer

A substance consisting of two or more elements in a fixed ratio.

Question 2

What percentage of the human body mass is made up of oxygen, carbon, hydrogen, and nitrogen combined?

Accepted Answer

About 96%

Question 3

Which subatomic particle determines the atomic number of an element?

Accepted Answer

Proton

Question 4

If an atom has 6 protons and 8 neutrons, what is its mass number?

Accepted Answer

$$14$$

Question 5

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have different numbers of neutrons.

Question 6

What is the main reason why sodium and chlorine form an ionic bond?

Accepted Answer

Sodium transfers an electron to chlorine, resulting in oppositely charged ions.

Question 7

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

Accepted Answer

Covalent bond

Question 8

What is the chemical equation for the formation of water from hydrogen and oxygen?

Accepted Answer

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

Question 9

Which of the following best describes a hydrogen bond?

Accepted Answer

A bond formed when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

Question 10

Which element is most abundant in the human body by mass?

Accepted Answer

Oxygen

Question 11

What is the term for electrons in the outermost shell of an atom?

Accepted Answer

Valence electrons

Question 12

Which of the following is true about chemical equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate.

Question 13

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

Accepted Answer

Zinc

Question 14

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

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity.

Question 15

Which of the following best explains why table salt (NaCl) has properties different from its constituent elements?

Accepted Answer

Emergent properties arise when elements combine to form compounds.

Question 16

Which equation represents photosynthesis?

Accepted Answer

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

Question 17

Which of the following is true about weak chemical interactions in biological molecules?

Accepted Answer

They help maintain the functional form of large biological molecules.

Question 18

What is the charge of a cation?

Accepted Answer

Positive

Question 19

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

Accepted Answer

They determine the chemical behavior and bonding capacity of an atom.

Question 20

Which statement about electron shells is correct?

Accepted Answer

Electrons have specific energy levels called shells.

Chapter 2: The Chemical Context of Life – Study Notes

Study Guide - Practice Questions