Q1. The balanced equation 3Fe + 4H₂O → Fe₃O₄ + 4H₂ uses water as:
A. Liquid ❌
B. Solid ❌
C. Steam ✅
D. Ice ❌
Why correct: The reaction occurs with steam, not liquid water.
Why others wrong: Liquid/solid/ice forms do not react like this with iron.
Q2. Symbol (g) represents:
A. Graph ❌
B. Gravity ❌
C. Gas ✅
D. Group ❌
Why correct: (g) is the standard symbol for gas state.
Why others wrong: They are not physical states in chemistry.
Q3. Water written as H₂O(g) indicates:
A. Liquid water ❌
B. Ice ❌
C. Steam ✅
D. Solution ❌
Why correct: (g) means gaseous state, i.e., steam.
Why others wrong: They represent other physical forms.
Q4. Physical states are usually written:
A. Always ❌
B. Never ❌
C. Only when needed ✅
D. Randomly ❌
Why correct: State symbols are added only when important.
Why others wrong: They are not compulsory every time.
Q5. Reaction conditions are written:
A. In brackets ❌
B. Inside formulas ❌
C. Above or below the arrow ✅
D. Separately ❌
Why correct: Conditions like heat/catalyst are written on the arrow.
Why others wrong: They are not part of substance formulas.
Q6. Temperature and pressure are examples of:
A. Reactants ❌
B. Products ❌
C. Reaction conditions ✅
D. Catalysts ❌
Why correct: They control how the reaction happens.
Why others wrong: They are not substances or chemicals.
Q7. Catalyst is written:
A. In formula ❌
B. Above arrow ✅
C. As reactant ❌
D. In product ❌
Why correct: Catalyst is shown over the arrow.
Why others wrong: It does not get used up.
Q8. Methanol formation occurs at:
A. High water level ❌
B. Cold temperature ❌
C. High pressure ✅
D. Room pressure ❌
Why correct: Industrial methanol needs high pressure.
Why others wrong: Reaction won’t proceed efficiently.
Q9. The reaction for glucose formation is an example of:
A. Respiration ❌
B. Fermentation ❌
C. Photosynthesis ✅
D. Combustion ❌
Why correct: Glucose is made in plants by photosynthesis.
Why others wrong: They break glucose, not form it.
Q10. Sunlight written below arrow represents:
A. Product ❌
B. Reactant ❌
C. Condition ✅
D. Chemical ❌
Why correct: Sunlight gives energy for the reaction.
Why others wrong: It is not a material reactant.
COMBINATION REACTIONS
Q11. Calcium oxide reacts with water to form:
A. Calcium carbonate ❌
B. Calcium sulphate ❌
C. Calcium hydroxide ✅
D. Calcium nitrate ❌
Why correct: CaO + H₂O → Ca(OH)₂.
Why others wrong: They have different compositions.
Q12. Chemical formula of quick lime is:
A. CaCO₃ ❌
B. CaO ✅
C. Ca(OH)₂ ❌
D. CaSO₄ ❌
Why correct: Quick lime is calcium oxide.
Why others wrong: They are other calcium compounds.
Q13. Slaked lime is:
A. CaO ❌
B. CaCO₃ ❌
C. Ca(OH)₂ ✅
D. CaCl₂ ❌
Why correct: Slaked lime = calcium hydroxide.
Why others wrong: Different formulas.
Q14. CaO + H₂O → Ca(OH)₂ is a:
A. Decomposition ❌
B. Combination ✅
C. Displacement ❌
D. Redox ❌
Why correct: Two substances combine to form one.
Why others wrong: No splitting or replacement.
Q15. Combination reaction forms:
A. Two products ❌
B. No product ❌
C. Single product ✅
D. Gas ❌
Why correct: Only one compound is made.
Why others wrong: They don’t define combination reactions.
Q16. Touching the beaker in Activity 5.4 shows:
A. Cooling ❌
B. Heating effect ✅
C. Colour change ❌
D. Sound ❌
Why correct: Heat is released.
Why others wrong: No such observation.
Q17. Calcium oxide reacting with water releases:
A. Cold ❌
B. Light ❌
C. Heat ✅
D. Gas ❌
Why correct: It is an exothermic reaction.
Why others wrong: No gas or light.
Q18. Reactions that release heat are:
A. Endothermic ❌
B. Neutral ❌
C. Exothermic ✅
D. Physical ❌
Why correct: Exo = release energy.
Why others wrong: Endo absorbs heat.
Q19. Whitewashing uses:
A. CaCO₃ ❌
B. CaO ❌
C. Ca(OH)₂ ✅
D. CaCl₂ ❌
Why correct: Slaked lime is used.
Why others wrong: They don’t form coating.
Q20. Slaked lime reacts with CO₂ to form:
A. CaSO₄ ❌
B. CaCO₃ ✅
C. CaO ❌
D. CaCl₂ ❌
Why correct: It forms calcium carbonate layer.
Why others wrong: Different chemicals.
Q21. Marble has chemical formula:
A. CaO ❌
B. Ca(OH)₂ ❌
C. CaCO₃ ✅
D. CaSO₄ ❌
Why correct: Marble is calcium carbonate.
Why others wrong: Not marble.
Q22. Shiny walls are due to formation of:
A. Calcium oxide ❌
B. Calcium sulphate ❌
C. Calcium carbonate ✅
D. Calcium hydroxide ❌
Why correct: Hard CaCO₃ gives shine.
Why others wrong: Not responsible for gloss.
Q23. Burning of coal produces:
A. CO ❌
B. CO₂ ✅
C. O₂ ❌
D. SO₂ ❌
Why correct: Carbon + oxygen → CO₂.
Why others wrong: They come from other fuels.
Q24. Burning of carbon is a:
A. Decomposition ❌
B. Combination ✅
C. Displacement ❌
D. Precipitation ❌
Why correct: Carbon combines with oxygen.
Why others wrong: No splitting or exchange.
Q25. Formation of water from H₂ and O₂ is:
A. Decomposition ❌
B. Combination ✅
C. Double displacement ❌
D. Neutralization ❌
Why correct: One product is formed.
Why others wrong: No ions or exchange.
Q26. 2H₂ + O₂ → 2H₂O shows:
A. Separation ❌
B. Combination ✅
C. Neutralization ❌
D. Decomposition ❌
Why correct: Substances combine.
Why others wrong: Opposite processes.
Q27. CH₄ burning is example of:
A. Exothermic reaction ✅
B. Endothermic ❌
C. Neutral ❌
D. Photosynthesis ❌
Why correct: Heat is released.
Why others wrong: Methane burns, not stores energy.
Q28. Natural gas main component is:
A. CO₂ ❌
B. CH₄ ✅
C. H₂ ❌
D. CO ❌
Why correct: Methane is major part.
Why others wrong: Present only in traces.
Q29. Respiration is:
A. Endothermic ❌
B. Exothermic ✅
C. Physical ❌
D. Nuclear ❌
Why correct: Energy is released.
Why others wrong: It is a chemical process.
Q30. Respiration provides:
A. Water ❌
B. CO₂ ❌
C. Energy ✅
D. Sugar ❌
Why correct: Energy is main output.
Why others wrong: They are by-products.
EXOTHERMIC REACTIONS
Q31. Exothermic reaction means:
A. Heat absorbed ❌
B. Heat released ✅
C. Mass lost ❌
D. Light absorbed ❌
Why correct: Energy comes out.
Why others wrong: Incorrect definition.
Q32. Glucose plus oxygen forms:
A. Methane ❌
B. Water only ❌
C. CO₂, H₂O and energy ✅
D. Alcohol ❌
Why correct: This is respiration.
Why others wrong: Wrong products.
Q33. Chemical reaction in respiration is:
A. Combination ❌
B. Decomposition ❌
C. Cellular respiration ✅
D. Displacement ❌
Why correct: It is a biological oxidation process.
Why others wrong: They are reaction types, not process name.
Q34. C₆H₁₂O₆ is formula of:
A. Ethanol ❌
B. Glucose ✅
C. Starch ❌
D. Protein ❌
Why correct: Known formula of glucose.
Why others wrong: Different compounds.
Q35. Compost formation gives:
A. Cold ❌
B. Heat ✅
C. Light ❌
D. Sound ❌
Why correct: Decomposition releases heat.
Why others wrong: Not seen.
Q36. Compost formation is:
A. Endothermic ❌
B. Exothermic ✅
C. Neutral ❌
D. Nuclear ❌
Why correct: Heat produced.
Why others wrong: Not energy-absorbing.
Q37. Which reaction releases energy?
A. Respiration ✅
B. Photosynthesis ❌
C. Boiling ❌
D. Melting ❌
Why correct: Respiration releases energy.
Why others wrong: Physical changes.
Q38. Energy comes from:
A. Oxygen ❌
B. Glucose ✅
C. Nitrogen ❌
D. Carbon ❌
Why correct: Oxidation of glucose releases energy.
Why others wrong: Not fuel here.
Q39. Photosynthesis is opposite of:
A. Rusting ❌
B. Respiration ✅
C. Fermentation ❌
D. Decomposition ❌
Why correct: One stores energy, one releases.
Why others wrong: Not exact reverse.
Q40. Reactions giving heat are useful in:
A. Cooling ❌
B. Heating ✅
C. Freezing ❌
D. Melting ❌
Why correct: Heat can be used for warming.
Why others wrong: Opposite effect.
DECOMPOSITION REACTIONS
Q41. Decomposition reaction means:
A. Two combine ❌
B. One breaks ✅
C. One replaces ❌
D. Exchange ❌
Why correct: One compound splits.
Why others wrong: Describe other reactions.
Q42. Ferrous sulphate on heating gives:
A. FeO ❌
B. Fe₂O₃ ✅
C. FeCO₃ ❌
D. FeCl₃ ❌
Why correct: Final solid is ferric oxide.
Why others wrong: Not formed.
Q43. Colour of ferrous sulphate crystals is:
A. Blue ❌
B. Red ❌
C. Green ✅
D. White ❌
Why correct: It is pale green.
Why others wrong: Incorrect.
Q44. Heating FeSO₄ produces smell of:
A. Oxygen ❌
B. Burning sulphur ✅
C. Hydrogen ❌
D. CO₂ ❌
Why correct: Due to SO₂ and SO₃ gases.
Why others wrong: No such gases formed.
Q45. Products of FeSO₄ heating include:
A. Fe₂O₃, SO₂, SO₃ ✅
B. FeO and CO₂ ❌
C. FeCl₃ and H₂ ❌
D. Fe(OH)₂ ❌
Why correct: Standard decomposition products.
Why others wrong: Wrong chemistry.
Q46. Fe₂O₃ is:
A. Ferric oxide ✅
B. Ferrous oxide ❌
C. Iron sulphate ❌
D. Iron hydroxide ❌
Why correct: Fe³⁺ oxide.
Why others wrong: Different compounds.
Q47. SO₂ and SO₃ are:
A. Solids ❌
B. Liquids ❌
C. Gases ✅
D. Solutions ❌
Why correct: Both are gases.
Why others wrong: Not true.
Q48. Loss of water from FeSO₄ is called:
A. Oxidation ❌
B. Dehydration ✅
C. Neutralization ❌
D. Combination ❌
Why correct: Water removal = dehydration.
Why others wrong: Different meaning.
Q49. Reaction done by heating is:
A. Chemical reaction ❌
B. Thermal decomposition ✅
C. Combination ❌
D. Catalysis ❌
Why correct: Heat breaks compound.
Why others wrong: Not specific.
Q50. CaCO₃ on heating gives:
A. CaO and CO ❌
B. CaCl₂ and O₂ ❌
C. CaO and CO₂ ✅
D. CaCO₃ only ❌
Why correct: Limestone decomposes.
Why others wrong: Not actual products.
INDUSTRIAL & APPLICATION
Q51. Limestone is:
A. CaO ❌
B. CaCO₃ ✅
C. Ca(OH)₂ ❌
D. CaSO₄ ❌
Why correct: Limestone is CaCO₃.
Why others wrong: Different compounds.
Q52. Quick lime is used in:
A. Paint ❌
B. Cement ✅
C. Plastic ❌
D. Petrol ❌
Why correct: Essential in cement making.
Why others wrong: Not used.
Q53. Product of CaCO₃ decomposition is:
A. Slaked lime ❌
B. Quick lime ✅
C. Marble ❌
D. Sand ❌
Why correct: CaO is quicklime.
Why others wrong: Wrong result.
Q54. Thermal decomposition needs:
A. Water ❌
B. Pressure ❌
C. Heat ✅
D. Light ❌
Why correct: Heat breaks bonds.
Why others wrong: Not required.
Q55. CaO is also called:
A. Slaked lime ❌
B. Quick lime ✅
C. Limestone ❌
D. Cement ❌
Why correct: CaO is quicklime.
Why others wrong: Different substances.
Q56. Which changes colour on heating?
A. NaCl ❌
B. FeSO₄ ✅
C. CaCO₃ ❌
D. CaO ❌
Why correct: Green → brown.
Why others wrong: No color change.
Q57. Which reaction has one reactant and many products?
A. Combination ❌
B. Decomposition ✅
C. Displacement ❌
D. Neutralization ❌
Why correct: One compound breaks.
Why others wrong: Opposite.
Q58. Quick lime is obtained from:
A. Marble ❌
B. Limewater ❌
C. Limestone ✅
D. Cement ❌
Why correct: CaCO₃ is heated.
Why others wrong: Not sources.
Q59. SO₃ is:
A. Sulphur monoxide ❌
B. Sulphur trioxide ✅
C. Sulphur dioxide ❌
D. Sulphur tetroxide ❌
Why correct: Three oxygen atoms.
Why others wrong: Incorrect prefix.
Q60. Decomposition reaction is opposite of:
A. Combination ✅
B. Neutralization ❌
C. Respiration ❌
D. Oxidation ❌
Why correct: Combination forms one; decomposition breaks.
Q61. Which reaction gives shiny walls?
A. CaO + H₂O ❌
B. Ca(OH)₂ + CO₂ ✅
C. CaCO₃ + heat ❌
D. Ca + O₂ ❌
Why correct: Whitewash reacts with CO₂ to form CaCO₃, giving shine.
Why others wrong: They don’t form the glossy layer.
Q62. A reaction forming energy is:
A. Respiration ✅
B. Melting ❌
C. Freezing ❌
D. Boiling ❌
Why correct: Respiration releases energy.
Why others wrong: These are physical changes.
Q63. Energy is released in:
A. Exothermic ✅
B. Endothermic ❌
C. Physical ❌
D. Nuclear ❌
Why correct: Exothermic = energy given out.
Why others wrong: Endothermic absorbs energy.
Q64. Methane burning gives:
A. CO + H₂O ❌
B. CO₂ + H₂O ✅
C. CO₂ only ❌
D. Soot only ❌
Why correct: Complete combustion forms CO₂ and water.
Why others wrong: Incomplete/incorrect results.
Q65. Reaction with single product is:
A. Decomposition ❌
B. Combination ✅
C. Displacement ❌
D. Precipitation ❌
Why correct: Combination forms one product.
Why others wrong: They create multiple products.
Q66. Ferrous sulphate loses water first due to:
A. Oxidation ❌
B. Heating ✅
C. Cooling ❌
D. Mixing ❌
Why correct: Heating removes water (dehydration).
Why others wrong: No water loss.
Q67. Ferric oxide is:
A. FeSO₄ ❌
B. Fe₂O₃ ✅
C. FeO ❌
D. FeS ❌
Why correct: Fe₂O₃ = ferric oxide.
Why others wrong: Wrong compounds.
Q68. Which is green in colour?
A. Ferric oxide ❌
B. Ferrous sulphate ✅
C. Calcium hydroxide ❌
D. Limestone ❌
Why correct: FeSO₄ crystals are green.
Why others wrong: Different colours.
Q69. Which reaction involves breaking of bonds?
A. Combination ❌
B. Decomposition ✅
C. Respiration ❌
D. Photosynthesis ❌
Why correct: Bonds are broken in decomposition.
Why others wrong: Opposite process.
Q70. Chemical reactions involve:
A. Breaking and making bonds ✅
B. Colour only ❌
C. Heat only ❌
D. Noise only ❌
Why correct: All chemistry involves bonds.
Why others wrong: Incomplete ideas.
FINAL SET
Q71. Which reaction gives heat and one product?
A. Decomposition ❌
B. Combination ✅
C. Displacement ❌
D. Neutralization ❌
Why correct: Combination can be exothermic.
Why others wrong: Don’t give single product.
Q72. Which compound decomposes on heating?
A. NaCl ❌
B. CaCO₃ ✅
C. CaO ❌
D. H₂O ❌
Why correct: Limestone breaks into CaO & CO₂.
Why others wrong: Stable or no decomposition.
Q73. CO₂ is produced by:
A. Respiration ✅
B. Combustion ✅
C. Decomposition ✅
D. All of these ✅
Why correct: All produce CO₂.
Why others wrong: Not applying “all”.
Q74. Energy is released in:
A. Exothermic ✅
B. Neutral ❌
C. Endothermic ❌
D. Inactive ❌
Why correct: Energy flows out.
Why others wrong: Wrong meaning.
Q75. Which reaction needs heat?
A. Respiration ❌
B. Decomposition ✅
C. Combination ❌
D. Photosynthesis ❌
Why correct: Thermal decomposition uses heat.
Why others wrong: Others don’t need heat start.
Q76. Which one releases heat always?
A. Endothermic ❌
B. Exothermic ✅
C. Physical ❌
D. Nuclear ❌
Why correct: Definition of exothermic.
Why others wrong: Opposite or irrelevant.
Q77. Which gas is formed in respiration?
A. Oxygen ❌
B. CO₂ ✅
C. Hydrogen ❌
D. Nitrogen ❌
Why correct: CO₂ is a waste gas.
Why others wrong: Not released.
Q78. Which reaction uses sunlight?
A. Respiration ❌
B. Photosynthesis ✅
C. Neutralization ❌
D. Combustion ❌
Why correct: Light energy needed.
Why others wrong: No light required.
Q79. A reaction with heat absorption is:
A. Exothermic ❌
B. Endothermic ✅
C. Neutral ❌
D. Atomic ❌
Why correct: Heat is absorbed.
Why others wrong: Opposite meanings.
Q80. Limestone breaks into:
A. Ca(OH)₂ ❌
B. CaO + CO₂ ✅
C. CaSO₄ ❌
D. CaCl₂ ❌
Why correct: Thermal decomposition products.
Why others wrong: Incorrect reactions.
Q81. Green crystals belong to:
A. Calcium sulphate ❌
B. Ferrous sulphate ✅
C. Zinc sulphate ❌
D. Copper sulphate ❌
Why correct: FeSO₄ appears green.
Why others wrong: Different colours.
Q82. What changes during decomposition?
A. Colour ❌
B. State ❌
C. Chemical nature ✅
D. Shape ❌
Why correct: A new substance forms.
Why others wrong: Only physical changes.
Q83. FeSO₄ breaks into how many products?
A. One ❌
B. Two ❌
C. Three ✅
D. Four ❌
Why correct: Fe₂O₃, SO₂, SO₃.
Why others wrong: Wrong count.
Q84. Ferrous sulphate has formula:
A. Fe₂O₃ ❌
B. FeSO₄ ✅
C. FeS ❌
D. FeCO₃ ❌
Why correct: Known formula.
Why others wrong: Wrong compounds.
Q85. Which reaction produces gas and solid?
A. CaO formation ❌
B. FeSO₄ heating ✅
C. Respiration ❌
D. Whitewashing ❌
Why correct: Produces gases + iron oxide.
Why others wrong: Do not form solid+gas.
Q86. Solid in FeSO₄ decomposition is:
A. SO₂ ❌
B. SO₃ ❌
C. Fe₂O₃ ✅
D. CO₂ ❌
Why correct: Brown solid remains.
Why others wrong: Gases.
Q87. Reaction forming CaCO₃ is:
A. Combination ✅
B. Decomposition ❌
C. Displacement ❌
D. Neutralization ❌
Why correct: Two combine into one.
Why others wrong: Different mechanisms.
Q88. Energy is stored in:
A. Glucose ✅
B. CO₂ ❌
C. Oxygen ❌
D. Water ❌
Why correct: Glucose stores chemical energy.
Why others wrong: Waste or reactive gases.
Q89. Bond breaking requires:
A. Energy ✅
B. Cooling ❌
C. Water ❌
D. Light only ❌
Why correct: Bonds need energy to break.
Why others wrong: Not universal.
Q90. Bond making releases:
A. Cold ❌
B. Energy ✅
C. Mass ❌
D. Gas ❌
Why correct: Energy stored is released.
Why others wrong: No relation.
Q91. Which reaction uses heat to break compound?
A. Combination ❌
B. Decomposition ✅
C. Respiration ❌
D. Neutralization ❌
Why correct: Heat breaks compound.
Why others wrong: No heating role.
Q92. Reaction forming Ca(OH)₂ is:
A. Neutralization ❌
B. Combination ✅
C. Decomposition ❌
D. Precipitation ❌
Why correct: Two combine.
Why others wrong: No exchange.
Q93. Calcium hydroxide solution is:
A. Limewater ✅
B. Acid ❌
C. Base ❌
D. Salt ❌
Why correct: Ca(OH)₂ in water = limewater.
Why others wrong: Wrong classification.
Q94. Marble is a form of:
A. CaO ❌
B. Ca(OH)₂ ❌
C. CaCO₃ ✅
D. CaCl₂ ❌
Why correct: Marble = calcium carbonate.
Why others wrong: Different compounds.
Q95. Which releases sulphur smell?
A. CaCO₃ ❌
B. FeSO₄ ✅
C. CaO ❌
D. NaCl ❌
Why correct: Due to SO₂/SO₃ gases.
Why others wrong: Not sulphur compounds.
Q96. Exothermic reactions feel:
A. Cold ❌
B. Warm ✅
C. Soft ❌
D. Wet ❌
Why correct: Heat is released.
Q97. Decomposition yields:
A. One product ❌
B. Two or more products ✅
C. No product ❌
D. Only gas ❌
Why correct: One substance splits.
Q98. Which requires breaking bonds?
A. Combination ❌
B. Decomposition ✅
C. Respiration ❌
D. Photosynthesis ❌
Why correct: Compound breaks.
Q99. Formation of water is a:
A. Decomposition ❌
B. Combination ✅
C. Neutralization ❌
D. Displacement ❌
Why correct: One product formed.
Q100. Which releases energy?
A. Exothermic reaction ✅
B. Endothermic reaction ❌
C. Freezing ❌
D. Melting ❌
Why correct: Energy goes out.
Why others wrong: Energy is absorbed.