,Chem 103 Module 3 | Exam study Questions and Answers + Rationales |
2026/27 Updates | 100% correct
1. According to the Portage Learning CHEM 103 Module 3 exam coverage, which of the
following is a primary topic for assessment?
A) Nuclear fission and fusion reactions
B) Nomenclature of inorganic compounds
C) Organic functional groups
D) Quantum mechanical models of the atom
Correct Answer: Nomenclature of inorganic compounds
Rationale: The CHEM 103 Module 3 exam specifically covers nomenclature of inorganic
compounds, chemical formula calculations, the mole concept, stoichiometry, and
empirical/molecular formulas . Nuclear chemistry, organic functional groups, and advanced
quantum models are covered in other modules or courses.
2. A chemist is analyzing a binary molecular compound consisting of phosphorus and chlorine.
The sample contains 1.25 moles of phosphorus and 6.25 moles of chlorine. What is the correct
IUPAC name for this compound?
A) Phosphorus chloride
B) Phosphorus pentachloride
C) Phosphorus(V) chloride
D) Pentaphosphorus chloride
Correct Answer: Phosphorus pentachloride
, Rationale: The mole ratio of phosphorus to chlorine is 1.25:6.25, which simplifies to 1:5,
giving the formula PCl₅. As a molecular compound, the correct nomenclature requires prefixes
to indicate the number of atoms, making it phosphorus pentachloride . Options A and C
incorrectly use ionic nomenclature or omit stoichiometry, and D uses the wrong prefix .
3. Which of the following is the correct formula for a compound formed between calcium and
phosphate?
A) CaPO₄
B) Ca₂(PO₄)₃
C) Ca₃(PO₄)₂
D) Ca(PO₄)₂
Correct Answer: Ca₃(PO₄)₂
Rationale: Calcium forms Ca²⁺ ions and phosphate is PO₄³⁻. To balance the charges, three Ca²⁺
ions (+6 total) are needed for two PO₄³⁻ ions (−6 total), resulting in the formula Ca₃(PO₄)₂.
4. What is the correct IUPAC name for the compound FeCl₂?
A) Iron chloride
B) Iron(II) chloride
C) Iron(III) chloride
D) Ferric chloride
Correct Answer: Iron(II) chloride
Rationale: Iron is a transition metal that can have multiple oxidation states. In FeCl₂, chloride
is −1 each, so Fe must be +2. The Roman numeral (II) indicates this oxidation state. FeCl₃ would
be Iron(III) chloride.
, 5. What is the correct IUPAC name for the covalent compound N₂O₅?
A) Nitrogen pentoxide
B) Dinitrogen oxide
C) Dinitrogen pentoxide
D) Nitrogen oxide
Correct Answer: Dinitrogen pentoxide
Rationale: For covalent compounds, prefixes indicate the number of atoms. "Di-" is used for
two nitrogen atoms and "penta-" for five oxygen atoms, giving dinitrogen pentoxide.
6. One mole of any substance contains exactly how many particles?
A) 6.02 × 10²³
B) 6.022 × 10²³
C) 6.022 × 10²²
D) 6.02 × 10²⁴
Correct Answer: 6.022 × 10²³
Rationale: Avogadro's number is 6.022 × 10²³ particles per mole . This is the number of atoms,
molecules, formula units, or ions in one mole of any substance. Option A is a common
approximation, but B is the exact value used in calculations.
7. What is the molar mass of sodium chloride (NaCl)?
A) 35.5 g/mol
B) 58.44 g/mol
2026/27 Updates | 100% correct
1. According to the Portage Learning CHEM 103 Module 3 exam coverage, which of the
following is a primary topic for assessment?
A) Nuclear fission and fusion reactions
B) Nomenclature of inorganic compounds
C) Organic functional groups
D) Quantum mechanical models of the atom
Correct Answer: Nomenclature of inorganic compounds
Rationale: The CHEM 103 Module 3 exam specifically covers nomenclature of inorganic
compounds, chemical formula calculations, the mole concept, stoichiometry, and
empirical/molecular formulas . Nuclear chemistry, organic functional groups, and advanced
quantum models are covered in other modules or courses.
2. A chemist is analyzing a binary molecular compound consisting of phosphorus and chlorine.
The sample contains 1.25 moles of phosphorus and 6.25 moles of chlorine. What is the correct
IUPAC name for this compound?
A) Phosphorus chloride
B) Phosphorus pentachloride
C) Phosphorus(V) chloride
D) Pentaphosphorus chloride
Correct Answer: Phosphorus pentachloride
, Rationale: The mole ratio of phosphorus to chlorine is 1.25:6.25, which simplifies to 1:5,
giving the formula PCl₅. As a molecular compound, the correct nomenclature requires prefixes
to indicate the number of atoms, making it phosphorus pentachloride . Options A and C
incorrectly use ionic nomenclature or omit stoichiometry, and D uses the wrong prefix .
3. Which of the following is the correct formula for a compound formed between calcium and
phosphate?
A) CaPO₄
B) Ca₂(PO₄)₃
C) Ca₃(PO₄)₂
D) Ca(PO₄)₂
Correct Answer: Ca₃(PO₄)₂
Rationale: Calcium forms Ca²⁺ ions and phosphate is PO₄³⁻. To balance the charges, three Ca²⁺
ions (+6 total) are needed for two PO₄³⁻ ions (−6 total), resulting in the formula Ca₃(PO₄)₂.
4. What is the correct IUPAC name for the compound FeCl₂?
A) Iron chloride
B) Iron(II) chloride
C) Iron(III) chloride
D) Ferric chloride
Correct Answer: Iron(II) chloride
Rationale: Iron is a transition metal that can have multiple oxidation states. In FeCl₂, chloride
is −1 each, so Fe must be +2. The Roman numeral (II) indicates this oxidation state. FeCl₃ would
be Iron(III) chloride.
, 5. What is the correct IUPAC name for the covalent compound N₂O₅?
A) Nitrogen pentoxide
B) Dinitrogen oxide
C) Dinitrogen pentoxide
D) Nitrogen oxide
Correct Answer: Dinitrogen pentoxide
Rationale: For covalent compounds, prefixes indicate the number of atoms. "Di-" is used for
two nitrogen atoms and "penta-" for five oxygen atoms, giving dinitrogen pentoxide.
6. One mole of any substance contains exactly how many particles?
A) 6.02 × 10²³
B) 6.022 × 10²³
C) 6.022 × 10²²
D) 6.02 × 10²⁴
Correct Answer: 6.022 × 10²³
Rationale: Avogadro's number is 6.022 × 10²³ particles per mole . This is the number of atoms,
molecules, formula units, or ions in one mole of any substance. Option A is a common
approximation, but B is the exact value used in calculations.
7. What is the molar mass of sodium chloride (NaCl)?
A) 35.5 g/mol
B) 58.44 g/mol
