Chemistry Past Paper PDF

Section 1: Multiple Choice (12 Questions) 1. What is the product of the combustion of methane (CH₄)? A) CO₂ and H₂O B) CO and H₂ C) C and H₂O D) CH₃COOH 2. Which of the following is an example of a neutralization reaction? A) NaOH + HCl → NaCl + H₂O B) C₃H₈ + O₂ → CO₂ + H₂O C) H₂ + Cl₂ → 2HCl D) C...

Section 1: Multiple Choice (12 Questions) 1. What is the product of the combustion of methane (CH₄)? A) CO₂ and H₂O B) CO and H₂ C) C and H₂O D) CH₃COOH 2. Which of the following is an example of a neutralization reaction? A) NaOH + HCl → NaCl + H₂O B) C₃H₈ + O₂ → CO₂ + H₂O C) H₂ + Cl₂ → 2HCl D) CaCO₃ + HCl → CaCl₂ + H₂O + CO₂ 3. In an exothermic reaction, energy is: A) Absorbed B) Released C) Neither D) Both 4. What type of reaction is represented by the equation 2H₂ + O₂ → 2H₂O? A) Decomposition B) Single replacement C) Synthesis D) Combustion 5. When an acid reacts with a carbonate, which of the following is NOT a product? A) Salt B) Water C) Hydrogen gas D) Carbon dioxide 6. What is the balanced equation for the reaction of acetic acid and sodium bicarbonate? A) CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂ B) CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O C) CH₃COOH + NaHCO₃ → Na + CO₂ + H₂O D) CH₃COOH + NaHCO₃ → CH₃COO + Na + H₂O 7. Which of the following is an endothermic reaction? A) Combustion of gasoline B) Photosynthesis C) Neutralization D) Respiration 8. The reaction 2Na + Cl₂ → 2NaCl is an example of what type of reaction? A) Synthesis B) Decomposition C) Single replacement D) Double replacement 9. Which product is formed when an acid reacts with a base? A) Salt and water B) Gas and water C) Salt and gas D) Water only 10. What type of reaction is represented by the equation: 2H₂O₂ → 2H₂O + O₂? A) Synthesis B) Decomposition C) Combustion D) Neutralization 11. Which of the following reactions produces carbon dioxide gas? A) NaOH + HCl B) CH₄ + O₂ C) NaHCO₃ + CH₃COOH D) Both B and C 12. In the reaction NaOH + HCl → NaCl + H₂O, what is the role of NaOH? A) Acid B) Base C) Salt D) Water Section 2: Balancing Chemical Equations (4 Questions) Balance the following equations: 1. C₃H₈ + 5O₂ → 3CO₂ + 4H₂O 2. H₂ + Cl₂ → 2HCl 3. 4Fe + 3O₂ → 2Fe₂O₃ 4. 2Na + 2H₂O → 2NaOH + H₂ Section 3: Writing Products of Reactions (8 Questions) Write the products of the following reactions and identify the type of reaction (e.g., synthesis, decomposition, single replacement, double replacement, combustion): 1. Combustion of ethane (C₂H₆): Products: carbon dioxide and water Type of Reaction: decomposition 2. Reaction between hydrochloric acid (HCl) and sodium carbonate (Na₂CO₃): Products: Type of Reaction: __________ 3. Decomposition of potassium chloride (KClO₃): Products: Potassium and chlorine Type of Reaction: decomposition 4. Reaction of zinc (Zn) with hydrochloric acid (HCl): Products: __________ Type of Reaction: __________ 5. Synthesis of aluminum oxide (Al₂O₃) from aluminum and oxygen: Products: __________ Type of Reaction: __________ 6. Neutralization of sulfuric acid (H₂SO₄) with potassium hydroxide (KOH): Products: __________ Type of Reaction: __________ 7. Single replacement reaction of iron (Fe) with copper sulfate (CuSO₄): Products: __________ Type of Reaction: __________  8. Reaction between sodium (Na) and water (H₂O): Products: __________ Type of Reaction: __________ Part A: Multiple Choice (12 Questions) Each question is worth 3 points. 1. Which of the following is a balanced chemical equation for the combustion of methane (CH₄)? a) CH₄ + O₂ → CO₂ + H₂O b) CH₄ + 2O₂ → CO₂ + 2H₂O c) CH₄ + 3O₂ → 2CO₂ + H₂O d) 2CH₄ + 4O₂ → 2CO₂ + 4H₂O 2. Which type of reaction does the following represent? Zn + HCl → ZnCl₂ + H₂ a) Synthesis b) Decomposition c) Single displacement d) Double displacement 3. What is the coefficient of O₂ when balancing the combustion reaction of ethanol (C₂H₅OH)? a) 1 b) 3 c) 5 d) 7 4. In a decomposition reaction, potassium chlorate (KClO₃) breaks down into potassium chloride (KCl) and oxygen gas (O₂). What is the balanced equation for this reaction? a) KClO₃ → KCl + O₂ b) 2KClO₃ → 2KCl + O₂ c) KClO₃ → KCl + 3O₂ d) 2KClO₃ → 2KCl + 3O₂ 5. Which of the following reactions is an example of a double displacement reaction?  a) NaOH + HCl → NaCl + H₂O b) 2H₂O₂ → 2H₂O + O₂ c) C₃H₈ + 5O₂ → 3CO₂ + 4H₂O d) Zn + 2HCl → ZnCl₂ + H₂ 6. When balancing the equation for the combustion of octane (C₈H₁₈), what is the coefficient of CO₂? a) 2 b) 8 c) 16 d) 18 7. Which of the following represents a synthesis reaction? a) N₂ + 3H₂ → 2NH₃ b) NaCl → Na + Cl₂ c) Fe + CuSO₄ → FeSO₄ + Cu d) H₂SO₄ → H₂O + SO₃ 8. What is the balanced equation for the combustion of butane (C₄H₁₀)? a) C₄H₁₀ + O₂ → CO₂ + H₂O b) 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O c) C₄H₁₀ + 5O₂ → 4CO₂ + 5H₂O d) 2C₄H₁₀ + O₂ → 4CO₂ + 5H₂O 9. Which of the following types of reactions does this equation represent? CaCO₃ → CaO + CO₂ a) Synthesis b) Decomposition c) Combustion d) Double displacement 10. In the reaction 2KClO₃ → 2KCl + 3O₂, what is the coefficient of O₂? a) 1 b) 2 c) 3 d) 4 11. Which of the following is a combustion reaction? a) C₆H₁₂O₆ + O₂ → CO₂ + H₂O b) MgO → Mg + O₂ c) H₂O₂ → H₂O + O₂ d) NaOH + H₂SO₄ → Na₂SO₄ + H₂O 12. Which of the following represents a decomposition reaction? a) 2K + Cl₂ → 2KCl  b) 2H₂O → 2H₂ + O₂ c) NaCl + AgNO₃ → NaNO₃ + AgCl d) 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O Part B: Balancing Chemical Equations (10 Questions) Each question is worth 4 points. 1. Balance the following equation: __C₃H₈ + __O₂ → __CO₂ + __H₂O 2. Balance the decomposition of aluminum oxide: __Al₂O₃ → __Al + __O₂ 3. Balance the combustion of hexane (C₆H₁₄): __C₆H₁₄ + __O₂ → __CO₂ + __H₂O 4. Balance the single displacement reaction between magnesium and hydrochloric acid: __Mg + __HCl → __MgCl₂ + __H₂ 5. Balance the synthesis reaction of ammonia from nitrogen and hydrogen: __N₂ + __H₂ → __NH₃ 6. Balance the decomposition of hydrogen peroxide: __H₂O₂ → __H₂O + __O₂ 7. Balance the combustion of ethyne (C₂H₂): __C₂H₂ + __O₂ → __CO₂ + __H₂O 8. Balance the reaction of iron with chlorine gas: __Fe + __Cl₂ → __FeCl₃ 9. Balance the reaction of sodium carbonate with hydrochloric acid: __Na₂CO₃ + __HCl → __NaCl + __H₂O + __CO₂ 10. Balance the combustion of glucose (C₆H₁₂O₆): __C₆H₁₂O₆ + __O₂ → __CO₂ + __H₂O Part C: Reaction Identification (8 Questions) Each question is worth 5 points.  1. Identify the type of reaction: 2Na+Cl2→2NaCl2Na+Cl2 →2NaCl Type: _______ 2. Identify the type of reaction: 2H2O2→2H2O+O22H2 O2 →2H2 O+O2 Type: _______ 3. Identify the type of reaction: CH4+2O2→CO2+2H2OCH4 +2O2 →CO2 +2H2 O Type: _______ 4. Identify the type of reaction: 2KClO3→2KCl+3O22KClO3 →2KCl+3O2 Type: _______ 5. Identify the type of reaction: C3H8+5O2→3CO2+4H2OC3 H8 +5O2 →3CO2 +4H2 O Type: _______ 6. Identify the type of reaction: Fe+CuSO4→FeSO4+CuFe+CuSO4 →FeSO4 +Cu Type: _______ 7. Identify the type of reaction: Zn+2HCl→ZnCl2+H2Zn+2HCl→ZnCl2 +H2 Type: _______ 8. Identify the type of reaction: H2SO4+2NaOH→Na2SO4+2H2OH2 SO4 +2NaOH→Na2 SO4 +2H2 O Type: _______ Part D: Creating Reactions (4 Questions) Each question is worth 6 points. 1. Write a combustion reaction that produces carbon dioxide and water. 2. Create a reaction that results in the production of oxygen gas. 3. Write a synthesis reaction that forms a compound from magnesium and oxygen. 4. Create a decomposition reaction that results in the production of water and oxygen. Part E: Error Identification and Correction (4 Questions) Each question is worth 7 points. 1. Identify and correct the mistake in this unbalanced equation: C4H10+O2→CO2+H2OC4 H10 +O2 →CO2 +H2 O Corrected equation: _______ 2. Identify and correct the mistake in this equation: H2SO4+NaOH→Na2SO4+H2H2 SO4 +NaOH→Na2 SO4 +H2 Corrected equation: _______ 3. Identify and correct the mistake in this equation: Fe+O2→FeOFe+O2 →FeO Corrected equation: _______ 4. Identify and correct the mistake in this equation: CaCO3→CaO+COCaCO3 →CaO+CO Corrected equation: _______