OBJECTIVE ASSESSMENT
200+ QUESTIONS & ANSWERS WITH
RATIONALES
,WGU D425 Introduction to Chemistry Objective Assessment
Question 1
Which statement best describes an element?
A. A substance composed of two or more chemically bonded elements
B. A pure substance that cannot be broken down by ordinary chemical means
C. A mixture with a uniform composition
D. A substance that always contains oxygen
Answer: B
Rationale: An element is a pure substance made of only one type of atom and cannot be
chemically broken down into simpler substances.
Question 2
What is the smallest particle of an element that retains the properties of that element?
A. Molecule
B. Proton
C. Atom
D. Compound
Answer: C
Rationale: An atom is the basic unit of an element that retains that element's chemical
properties.
Question 3
Which subatomic particle has a positive charge?
,A. Electron
B. Neutron
C. Proton
D. Photon
Answer: C
Rationale: Protons carry a positive charge and are located in the nucleus of an atom.
Question 4
The atomic number of an element represents the number of:
A. Neutrons
B. Protons
C. Electrons and neutrons combined
D. Energy levels
Answer: B
Rationale: The atomic number uniquely identifies an element and equals the number of
protons in its nucleus.
Question 5
A neutral atom has 12 protons and 12 electrons. What is its net charge?
A. +12
B. −12
C. +1
D. 0
Answer: D
, Rationale: A neutral atom has equal numbers of positively charged protons and negatively
charged electrons, resulting in no overall charge.
Question 6
An atom contains 17 protons and 18 electrons. What is the charge of the ion?
A. +1
B. −1
C. +17
D. −17
Answer: B
Rationale: The atom has one more electron than proton, giving it a net charge of −1.
Question 7
Isotopes of the same element differ in their number of:
A. Protons
B. Neutrons
C. Electrons only
D. Atomic numbers
Answer: B
Rationale: Isotopes have the same number of protons but different numbers of neutrons.
Question 8
What is the mass number of an atom with 11 protons and 12 neutrons?
200+ QUESTIONS & ANSWERS WITH
RATIONALES
,WGU D425 Introduction to Chemistry Objective Assessment
Question 1
Which statement best describes an element?
A. A substance composed of two or more chemically bonded elements
B. A pure substance that cannot be broken down by ordinary chemical means
C. A mixture with a uniform composition
D. A substance that always contains oxygen
Answer: B
Rationale: An element is a pure substance made of only one type of atom and cannot be
chemically broken down into simpler substances.
Question 2
What is the smallest particle of an element that retains the properties of that element?
A. Molecule
B. Proton
C. Atom
D. Compound
Answer: C
Rationale: An atom is the basic unit of an element that retains that element's chemical
properties.
Question 3
Which subatomic particle has a positive charge?
,A. Electron
B. Neutron
C. Proton
D. Photon
Answer: C
Rationale: Protons carry a positive charge and are located in the nucleus of an atom.
Question 4
The atomic number of an element represents the number of:
A. Neutrons
B. Protons
C. Electrons and neutrons combined
D. Energy levels
Answer: B
Rationale: The atomic number uniquely identifies an element and equals the number of
protons in its nucleus.
Question 5
A neutral atom has 12 protons and 12 electrons. What is its net charge?
A. +12
B. −12
C. +1
D. 0
Answer: D
, Rationale: A neutral atom has equal numbers of positively charged protons and negatively
charged electrons, resulting in no overall charge.
Question 6
An atom contains 17 protons and 18 electrons. What is the charge of the ion?
A. +1
B. −1
C. +17
D. −17
Answer: B
Rationale: The atom has one more electron than proton, giving it a net charge of −1.
Question 7
Isotopes of the same element differ in their number of:
A. Protons
B. Neutrons
C. Electrons only
D. Atomic numbers
Answer: B
Rationale: Isotopes have the same number of protons but different numbers of neutrons.
Question 8
What is the mass number of an atom with 11 protons and 12 neutrons?
