WGU D425 Intro to Chemistry Objective
Assessment Actual Exam 2025/2026 |
Questions with Verified Answers | 100%
Correct | Pass Guaranteed
SECTION 1: ATOMIC STRUCTURE & PERIODIC TRENDS
QUESTION 1
Where is the majority of the atomic mass concentration in an atom?
A) Orbitals
B) Nucleus
C) Shells
D) Subshells
Correct ,,,,answer,,,,: B
Rationale: The nucleus contains protons and neutrons, which account
for nearly all of an atom's mass. Electrons in orbitals/shells/subshells
contribute negligible mass. The mass number is the sum of protons and
neutrons in the nucleus .
,QUESTION 2
The following notation represents an atom in its neutral state: ¹⁴₇N.
How many protons, neutrons, and electrons does this element have?
A) Protons 7, neutrons 14, electrons 7
B) Protons 7, neutrons 7, electrons 7
C) Protons 14, neutrons 7, electrons 14
D) Protons 7, neutrons 14, electrons 14
Correct ,,,,answer,,,,: B
Rationale: The atomic number (subscript, 7) equals the number of
protons, which equals the number of electrons in a neutral atom. The
mass number (superscript, 14) is protons + neutrons; neutrons = 14 - 7 =
7. Thus, 7 protons, 7 neutrons, 7 electrons .
QUESTION 3
What is the trend for atomic radius on the periodic table?
A) Increases from left to right across a period and decreases down a
group
B) Decreases from left to right across a period and increases down a
group
C) Increases from left to right and increases down a group
D) Decreases from left to right and decreases down a group
Correct ,,,,answer,,,,: B
,Rationale: Atomic radius decreases across a period due to increased
effective nuclear charge pulling electrons closer. It increases down a
group because additional electron shells are added .
QUESTION 4
How do you determine the charge of an ion for a main-group
element?
A) Use the group number: metals gain electrons to form negative anions;
non-metals lose electrons to form positive cations
B) Use the group number: metals lose electrons to form positive cations;
non-metals gain electrons to form negative anions
C) Use the period number to determine ion charge
D) Ion charge is independent of group number
Correct ,,,,answer,,,,: B
Rationale: Metals tend to lose electrons to achieve a stable octet,
forming positive cations (e.g., Group 1 → +1). Non-metals gain
electrons to form negative anions (e.g., Group 17 → -1) .
QUESTION 5
Isotopes are atoms of the same element that:
A) Have the same number of protons but different numbers of neutrons
B) Have different numbers of protons but the same number of neutrons
, C) Have the same number of protons and neutrons
D) Have different numbers of protons and electrons
Correct ,,,,answer,,,,: A
Rationale: Isotopes of an element have the same atomic number
(protons) but different mass numbers due to different neutron counts.
For example, ¹²C and ¹⁴C are both carbon isotopes .
QUESTION 6
What is a compound?
A) A combination of two or more pure substances that retains its own
identity and properties
B) A substance made up of two or more different elements joined
together in a fixed ratio
C) A single element in its pure form
D) A mixture of elements and compounds
Correct ,,,,answer,,,,: B
Rationale: A compound is a substance composed of two or more
different elements chemically bonded in a fixed, definite ratio. Examples
include H₂O and NaCl. This distinguishes compounds from mixtures,
which retain individual identities .
QUESTION 7
Assessment Actual Exam 2025/2026 |
Questions with Verified Answers | 100%
Correct | Pass Guaranteed
SECTION 1: ATOMIC STRUCTURE & PERIODIC TRENDS
QUESTION 1
Where is the majority of the atomic mass concentration in an atom?
A) Orbitals
B) Nucleus
C) Shells
D) Subshells
Correct ,,,,answer,,,,: B
Rationale: The nucleus contains protons and neutrons, which account
for nearly all of an atom's mass. Electrons in orbitals/shells/subshells
contribute negligible mass. The mass number is the sum of protons and
neutrons in the nucleus .
,QUESTION 2
The following notation represents an atom in its neutral state: ¹⁴₇N.
How many protons, neutrons, and electrons does this element have?
A) Protons 7, neutrons 14, electrons 7
B) Protons 7, neutrons 7, electrons 7
C) Protons 14, neutrons 7, electrons 14
D) Protons 7, neutrons 14, electrons 14
Correct ,,,,answer,,,,: B
Rationale: The atomic number (subscript, 7) equals the number of
protons, which equals the number of electrons in a neutral atom. The
mass number (superscript, 14) is protons + neutrons; neutrons = 14 - 7 =
7. Thus, 7 protons, 7 neutrons, 7 electrons .
QUESTION 3
What is the trend for atomic radius on the periodic table?
A) Increases from left to right across a period and decreases down a
group
B) Decreases from left to right across a period and increases down a
group
C) Increases from left to right and increases down a group
D) Decreases from left to right and decreases down a group
Correct ,,,,answer,,,,: B
,Rationale: Atomic radius decreases across a period due to increased
effective nuclear charge pulling electrons closer. It increases down a
group because additional electron shells are added .
QUESTION 4
How do you determine the charge of an ion for a main-group
element?
A) Use the group number: metals gain electrons to form negative anions;
non-metals lose electrons to form positive cations
B) Use the group number: metals lose electrons to form positive cations;
non-metals gain electrons to form negative anions
C) Use the period number to determine ion charge
D) Ion charge is independent of group number
Correct ,,,,answer,,,,: B
Rationale: Metals tend to lose electrons to achieve a stable octet,
forming positive cations (e.g., Group 1 → +1). Non-metals gain
electrons to form negative anions (e.g., Group 17 → -1) .
QUESTION 5
Isotopes are atoms of the same element that:
A) Have the same number of protons but different numbers of neutrons
B) Have different numbers of protons but the same number of neutrons
, C) Have the same number of protons and neutrons
D) Have different numbers of protons and electrons
Correct ,,,,answer,,,,: A
Rationale: Isotopes of an element have the same atomic number
(protons) but different mass numbers due to different neutron counts.
For example, ¹²C and ¹⁴C are both carbon isotopes .
QUESTION 6
What is a compound?
A) A combination of two or more pure substances that retains its own
identity and properties
B) A substance made up of two or more different elements joined
together in a fixed ratio
C) A single element in its pure form
D) A mixture of elements and compounds
Correct ,,,,answer,,,,: B
Rationale: A compound is a substance composed of two or more
different elements chemically bonded in a fixed, definite ratio. Examples
include H₂O and NaCl. This distinguishes compounds from mixtures,
which retain individual identities .
QUESTION 7
