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WGU D425 Intro to Chemistry Objective
Assessment Exam 2025/2026 – Accurate
Questions with Correct Detailed Answers
(100% Guaranteed Pass)
Question 1
What is the smallest unit of an element that retains its chemical properties?
A. Molecule
B. Atom
C. Ion
D. Compound
Correct Answer: B. Atom
Rationale: An atom is the smallest unit of an element that retains its chemical properties,
consisting of a nucleus and electrons. Molecules are formed from multiple atoms, ions are
charged atoms, and compounds are substances made of different elements.
Question 2
Which subatomic particle has a positive charge?
A. Electron
B. Neutron
C. Proton
D. Photon
Correct Answer: C. Proton
Rationale: Protons carry a positive charge and are located in the nucleus of an atom.
Electrons are negatively charged, neutrons are neutral, and photons are particles of light, not
subatomic particles.
Question 3
What is the atomic number of an element?
A. Number of neutrons
B. Number of protons
, 2
C. Number of electrons
D. Total number of protons and neutrons
Correct Answer: B. Number of protons
Rationale: The atomic number is the number of protons in an atom’s nucleus, defining the
element’s identity. Neutrons contribute to mass, electrons balance charge, and the sum of protons
and neutrons is the mass number.
Question 4
How many electrons can the first energy level of an atom hold?
A. 2
B. 8
C. 18
D. 32
Correct Answer: A. 2
Rationale: The first energy level (n=1) can hold a maximum of 2 electrons, following the
formula 2n², where n is the energy level.
Question 5
What is the mass number of an atom with 6 protons and 7 neutrons?
A. 6
B. 7
C. 13
D. 19
Correct Answer: C. 13
Rationale: The mass number is the sum of protons and neutrons. For an atom with 6 protons
and 7 neutrons, 6 + 7 = 13.
Question 6
Which element has the electron configuration 1s² 2s² 2p⁴?
A. Nitrogen
B. Oxygen
C. Fluorine
D. Carbon
, 3
Correct Answer: B. Oxygen
Rationale: The electron configuration 1s² 2s² 2p⁴ has 8 electrons, corresponding to oxygen
(atomic number 8). Nitrogen has 7 electrons, fluorine has 9, and carbon has 6.
Question 7
What type of bond forms between sodium and chlorine in NaCl?
A. Covalent
B. Ionic
C. Metallic
D. Hydrogen
Correct Answer: B. Ionic
Rationale: Sodium (metal) transfers an electron to chlorine (nonmetal), forming an ionic
bond due to electrostatic attraction between Na⁺ and Cl⁻.
Question 8
Which molecule has a nonpolar covalent bond?
A. HCl
B. H₂O
C. N₂
D. NH₃
Correct Answer: C. N₂
Rationale: N₂ has a nonpolar covalent bond because both nitrogen atoms have identical
electronegativity, sharing electrons equally. HCl, H₂O, and NH₃ have polar bonds due to
electronegativity differences.
Question 9
What is the shape of a water molecule?
A. Linear
B. Bent
C. Tetrahedral
D. Trigonal planar
WGU D425 Intro to Chemistry Objective
Assessment Exam 2025/2026 – Accurate
Questions with Correct Detailed Answers
(100% Guaranteed Pass)
Question 1
What is the smallest unit of an element that retains its chemical properties?
A. Molecule
B. Atom
C. Ion
D. Compound
Correct Answer: B. Atom
Rationale: An atom is the smallest unit of an element that retains its chemical properties,
consisting of a nucleus and electrons. Molecules are formed from multiple atoms, ions are
charged atoms, and compounds are substances made of different elements.
Question 2
Which subatomic particle has a positive charge?
A. Electron
B. Neutron
C. Proton
D. Photon
Correct Answer: C. Proton
Rationale: Protons carry a positive charge and are located in the nucleus of an atom.
Electrons are negatively charged, neutrons are neutral, and photons are particles of light, not
subatomic particles.
Question 3
What is the atomic number of an element?
A. Number of neutrons
B. Number of protons
, 2
C. Number of electrons
D. Total number of protons and neutrons
Correct Answer: B. Number of protons
Rationale: The atomic number is the number of protons in an atom’s nucleus, defining the
element’s identity. Neutrons contribute to mass, electrons balance charge, and the sum of protons
and neutrons is the mass number.
Question 4
How many electrons can the first energy level of an atom hold?
A. 2
B. 8
C. 18
D. 32
Correct Answer: A. 2
Rationale: The first energy level (n=1) can hold a maximum of 2 electrons, following the
formula 2n², where n is the energy level.
Question 5
What is the mass number of an atom with 6 protons and 7 neutrons?
A. 6
B. 7
C. 13
D. 19
Correct Answer: C. 13
Rationale: The mass number is the sum of protons and neutrons. For an atom with 6 protons
and 7 neutrons, 6 + 7 = 13.
Question 6
Which element has the electron configuration 1s² 2s² 2p⁴?
A. Nitrogen
B. Oxygen
C. Fluorine
D. Carbon
, 3
Correct Answer: B. Oxygen
Rationale: The electron configuration 1s² 2s² 2p⁴ has 8 electrons, corresponding to oxygen
(atomic number 8). Nitrogen has 7 electrons, fluorine has 9, and carbon has 6.
Question 7
What type of bond forms between sodium and chlorine in NaCl?
A. Covalent
B. Ionic
C. Metallic
D. Hydrogen
Correct Answer: B. Ionic
Rationale: Sodium (metal) transfers an electron to chlorine (nonmetal), forming an ionic
bond due to electrostatic attraction between Na⁺ and Cl⁻.
Question 8
Which molecule has a nonpolar covalent bond?
A. HCl
B. H₂O
C. N₂
D. NH₃
Correct Answer: C. N₂
Rationale: N₂ has a nonpolar covalent bond because both nitrogen atoms have identical
electronegativity, sharing electrons equally. HCl, H₂O, and NH₃ have polar bonds due to
electronegativity differences.
Question 9
What is the shape of a water molecule?
A. Linear
B. Bent
C. Tetrahedral
D. Trigonal planar
