PES SS 1 Chemistry (Obj) 3rd Term Exam 2025/2026
  • 1. Organic chemistry is the study of
A) Water
B) Metals
C) Carbon compounds
D) Salts
  • 2. Which of the following is an organic compound?
A) H2SO4
B) NaCl
C) CH4
D) CO2
  • 3. The element present in all organic compounds is
A) Carbon
B) Hydrogen
C) Oxygen
D) Nitrogen
  • 4. Organic compounds generally have
A) High melting points
B) High electrical conductivity
C) Low melting and boiling points
D) Metallic bonding
  • 5. Which property is common to most organic compounds?
A) Good conductors of electricity
B) Insoluble in water
C) Ionic in nature
D) Soluble in water
  • 6. The ability of carbon atoms to join together is called
A) Polymerization
B) Catenation
C) Catalysis
D) Isomerism
  • 7. Organic compounds mainly contain _____ bonds.
A) Electrovalent
B) Metallic
C) Ionic
D) Covalent
  • 8. Which of these is NOT an organic compound?
A) Methane
B) Sodium carbonate
C) Benzene
D) Ethanol
  • 9. The general formula of alkanes is
A) CₙH₂ₙ₋₂
B) CₙH₂ₙ₊₂
C) CₙHₙ
D) CₙH₂ₙ
  • 10. Alkanes contain only
A) Double bonds
B) Triple bonds
C) Ionic bonds
D) Single bonds
  • 11. Ethene belongs to the
A) Alkane family
B) Alkene family
C) Alkyne family
D) Alcohol family
  • 12. The functional group of alkenes is
A) –COOH
B) C=C
C) C≡C
D) –OH
  • 13. Ethyne belongs to the
A) Alkane family
B) Alkyne family
C) Ester family
D) Alkene family
  • 14. The general formula of alkenes is
A) CₙH₂ₙ₋₂
B) CₙH₂ₙ₊₂
C) CₙH₂ₙ
D) CₙHₙ
  • 15. The molecular formula of propane is
A) C₃H₈
B) C₃H₆
C) CH₄
D) C₃H₄
  • 16. Which hydrocarbon is unsaturated?
A) Ethene
B) Propane
C) Butane
D) Methane
  • 17. The general formula of alkynes is
A) CₙH₂ₙ
B) CₙH₂ₙ₋₂
C) CₙH₂ₙ₊₂
D) CₙHₙ
  • 18. Which compound decolourises bromine water?
A) Propane
B) Ethene
C) Ethane
D) Methane
  • 19. Which hydrocarbon has the formula C₂H₆?
A) Propene
B) Ethene
C) Ethane
D) Ethyne
  • 20. Homologous series members differ by
A) H₂
B) CH₂
C) CO₂
D) CH₄
  • 21. Isomerism is the existence of compounds with
A) Same colour
B) Same state
C) Same formula and different structures
D) Different formulae
  • 22. Structural isomers have
A) Same molecular formula but different structural formula
B) Same boiling point always
C) Different molecular formula
D) Same physical properties
  • 23. Which compound shows geometric isomerism?
A) Ethane
B) Methane
C) Ethene
D) Propane
  • 24. Cis-trans isomerism is another name for
A) Geometric isomerism
B) Nuclear isomerism
C) Optical isomerism
D) Structural isomerism
  • 25. Isomers have
A) Different molecular formula
B) Same empirical formula only
C) Different atomic masses
D) Same molecular formula
  • 26. Which of these is NOT a type of isomerism taught at this level?
A) Structural
B) Geometric
C) Nuclear
D) Chain
  • 27. Petroleum is also known as
A) Coal
B) Coke
C) Bitumen
D) Crude oil
  • 28. Petroleum is separated into fractions by
A) Filtration
B) Fractional distillation
C) Evaporation
D) Distillation
  • 29. Petrol is mainly used as
A) Fuel for cars
B) Lubricant
C) Roofing material
D) Road surfacing
  • 30. Petrochemicals are products obtained from
A) Wood
B) Petroleum
C) Coal
D) Water
  • 31. Which of these is a petrochemical product?
A) Sand
B) Plastic
C) Glass
D) Salt
  • 32. A chemical reaction produces
A) A new substance
B) Oxygen only
C) No new substance
D) Water only
  • 33. A combination reaction involves
A) One substance breaking down
B) Exchange of ions
C) Neutralization only
D) Two or more substances combining
  • 34. A decomposition reaction involves
A) Combining elements
B) Breaking one compound into simpler substances
C) Burning fuel
D) Dissolving salts
  • 35. Rusting of iron is an example of
A) Melting
B) Sublimation
C) Physical change
D) Chemical change
  • 36. Burning of wood is a
A) Physical change
B) Chemical change
C) Mechanical change
D) Reversible change
  • 37. Which is NOT evidence of a chemical reaction?
A) Change in shape only
B) Formation of precipitate
C) Colour change
D) Gas evolution
  • 38. An exothermic reaction
A) Absorbs heat
B) Has no heat change
C) Releases heat
D) Produces electricity only
  • 39. An endothermic reaction
A) Produces flame
B) Absorbs heat
C) Gives out heat
D) Is always explosive
  • 40. Combustion is generally
A) Exothermic
B) Reversible
C) Neutral
D) Endothermic
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