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