Question 1

Which of the following statements best explains why sodium (Na) and chlorine (Cl) combine to form sodium chloride (NaCl)?

Accepted Answer

Sodium donates an electron to chlorine, resulting in the formation of oppositely charged ions that attract each other.

Question 2

Which element makes up the largest percentage of the human body by mass, and why is it so abundant?

Accepted Answer

Oxygen, because it is a major component of water and is involved in cellular respiration.

Question 3

A radioactive isotope of carbon, carbon-14, is used in radiometric dating. What makes carbon-14 different from the most common carbon isotope, carbon-12?

Accepted Answer

Carbon-14 has more neutrons than carbon-12.

Question 4

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of one or more pairs of electrons between atoms.

Question 5

Which of the following molecules contains a polar covalent bond?

Accepted Answer

H$$_2O$$

Question 6

What is the atomic number of an element, and how is it determined?

Accepted Answer

The atomic number is the number of protons in the nucleus.

Question 7

Which of the following best explains why water (H$$_2O) $$molecules are attracted to each other?

Accepted Answer

Water molecules form hydrogen bonds due to the partial charges on the oxygen and hydrogen atoms.

Question 8

A calcium ion (Ca$$^{2+}) $$has 20 protons, 20 neutrons, and 18 electrons. What is the charge of this ion, and why?

Accepted Answer

The ion has a $$+2$$ charge because it has two more protons than electrons.

Question 9

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 10

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is a group of atoms held together by covalent bonds, while a compound consists of two or more different elements in a fixed ratio.

Question 11

Which of the following elements is NOT one of the four most abundant elements in the human body?

Accepted Answer

Calcium

Question 12

Which of the following best explains why noble gases such as helium (He) are chemically inert?

Accepted Answer

They have a full valence shell of electrons.

Question 13

Which of the following is a real-world example of an ionic compound?

Accepted Answer

Sodium chloride (NaCl)

Question 14

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

Accepted Answer

$$15 - 7 = 8$$ neutrons

Question 15

Which of the following best describes electronegativity?

Accepted Answer

The ability of an atom to attract electrons in a covalent bond.

Question 16

Which of the following is true about hydrogen bonds?

Accepted Answer

They form between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom.

Question 17

A molecule of methane (CH$$_4) $$contains how many single covalent bonds?

Accepted Answer

Four

Question 18

Which of the following best explains why table salt (NaCl) dissolves easily in water?

Accepted Answer

The partial charges on water molecules surround and separate the Na$$^+$$ and Cl$$^-$$ ions.

Question 19

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

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Atomic mass} - 	ext{Atomic number}$$

Chapter 2: The Chemical Context of Life – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards