,CHEM 110 Exam 2 Chemistry chamberlain I Questions And Answers
2026/2027 Chamberlain
1.** Which of the following is the correct balanced equation for the reaction
between hydrogen gas and oxygen gas to form water?
A) H₂ + O₂ → H₂O
B) 2H₂ + O₂ → 2H₂O
C) H₂ + 2O₂ → H₂O
D) 2H₂ + 2O₂ → 2H₂O
**Correct Answer:** B) 2H₂ + O₂ → 2H₂O
**Rationale:** Balancing this reaction requires 2 molecules of H₂ and 1
molecule of O₂ to produce 2 molecules of H₂O, ensuring 4 hydrogen atoms
and 2 oxygen atoms on both sides of the equation.
**2.** In a chemical equation, the substances on the left side of the arrow
are called:
A) Products
B) Reactants
C) Coefficients
D) Catalysts
**Correct Answer:** B) Reactants
**Rationale:** Reactants are the starting substances in a chemical reaction
and are written on the left side of the arrow. Products (A) are the substances
,formed and written on the right side. Coefficients (C) are the numbers placed
in front of formulas to balance the equation.
**3.** What type of reaction occurs when a single compound breaks down
into two or more simpler substances?
A) Synthesis reaction
B) Decomposition reaction
C) Single replacement reaction
D) Combustion reaction
**Correct Answer:** B) Decomposition reaction
**Rationale:** A decomposition reaction involves a single compound
breaking down into two or more simpler substances (e.g., 2H₂O → 2H₂ + O₂).
A synthesis reaction (A) combines substances; a single replacement reaction
(C) involves an element replacing another in a compound; a combustion
reaction (D) involves oxygen.
**4.** Which of the following is the correctly balanced equation for the
reaction of sodium metal with chlorine gas?
A) Na + Cl₂ → NaCl
B) 2Na + Cl₂ → 2NaCl
C) Na + 2Cl₂ → NaCl₂
D) 2Na + 2Cl₂ → 2NaCl
**Correct Answer:** B) 2Na + Cl₂ → 2NaCl
, **Rationale:** Sodium (Na) has a +1 charge and chlorine (Cl) has a -1
charge, forming NaCl. Balancing requires 2 Na atoms and 1 Cl₂ molecule to
produce 2 NaCl units, ensuring equal atoms on both sides.
**5.** In the reaction 2Mg + O₂ → 2MgO, the coefficient of MgO is:
A) 1
B) 2
C) 3
D) 4
**Correct Answer:** B) 2
**Rationale:** The coefficient 2 in front of MgO indicates that 2 molecules of
magnesium oxide are produced in this balanced reaction.
**6.** Which of the following is a combination (synthesis) reaction?
A) 2H₂O → 2H₂ + O₂
B) Fe + S → FeS
C) Zn + 2HCl → ZnCl₂ + H₂
D) CH₄ + 2O₂ → CO₂ + 2H₂O
**Correct Answer:** B) Fe + S → FeS
**Rationale:** A synthesis reaction involves two or more simpler substances
combining to form a more complex compound. Fe + S → FeS is a synthesis
reaction. Option A is decomposition, C is single replacement, and D is
combustion.
2026/2027 Chamberlain
1.** Which of the following is the correct balanced equation for the reaction
between hydrogen gas and oxygen gas to form water?
A) H₂ + O₂ → H₂O
B) 2H₂ + O₂ → 2H₂O
C) H₂ + 2O₂ → H₂O
D) 2H₂ + 2O₂ → 2H₂O
**Correct Answer:** B) 2H₂ + O₂ → 2H₂O
**Rationale:** Balancing this reaction requires 2 molecules of H₂ and 1
molecule of O₂ to produce 2 molecules of H₂O, ensuring 4 hydrogen atoms
and 2 oxygen atoms on both sides of the equation.
**2.** In a chemical equation, the substances on the left side of the arrow
are called:
A) Products
B) Reactants
C) Coefficients
D) Catalysts
**Correct Answer:** B) Reactants
**Rationale:** Reactants are the starting substances in a chemical reaction
and are written on the left side of the arrow. Products (A) are the substances
,formed and written on the right side. Coefficients (C) are the numbers placed
in front of formulas to balance the equation.
**3.** What type of reaction occurs when a single compound breaks down
into two or more simpler substances?
A) Synthesis reaction
B) Decomposition reaction
C) Single replacement reaction
D) Combustion reaction
**Correct Answer:** B) Decomposition reaction
**Rationale:** A decomposition reaction involves a single compound
breaking down into two or more simpler substances (e.g., 2H₂O → 2H₂ + O₂).
A synthesis reaction (A) combines substances; a single replacement reaction
(C) involves an element replacing another in a compound; a combustion
reaction (D) involves oxygen.
**4.** Which of the following is the correctly balanced equation for the
reaction of sodium metal with chlorine gas?
A) Na + Cl₂ → NaCl
B) 2Na + Cl₂ → 2NaCl
C) Na + 2Cl₂ → NaCl₂
D) 2Na + 2Cl₂ → 2NaCl
**Correct Answer:** B) 2Na + Cl₂ → 2NaCl
, **Rationale:** Sodium (Na) has a +1 charge and chlorine (Cl) has a -1
charge, forming NaCl. Balancing requires 2 Na atoms and 1 Cl₂ molecule to
produce 2 NaCl units, ensuring equal atoms on both sides.
**5.** In the reaction 2Mg + O₂ → 2MgO, the coefficient of MgO is:
A) 1
B) 2
C) 3
D) 4
**Correct Answer:** B) 2
**Rationale:** The coefficient 2 in front of MgO indicates that 2 molecules of
magnesium oxide are produced in this balanced reaction.
**6.** Which of the following is a combination (synthesis) reaction?
A) 2H₂O → 2H₂ + O₂
B) Fe + S → FeS
C) Zn + 2HCl → ZnCl₂ + H₂
D) CH₄ + 2O₂ → CO₂ + 2H₂O
**Correct Answer:** B) Fe + S → FeS
**Rationale:** A synthesis reaction involves two or more simpler substances
combining to form a more complex compound. Fe + S → FeS is a synthesis
reaction. Option A is decomposition, C is single replacement, and D is
combustion.
