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