🧪 Carbon and Its Compounds – Class 10 Science MCQs

Part 2: Properties, Chemical Reactions of Carbon Compounds (Q26–Q50)

Q26. Which of the following hydrocarbons burns with a sooty flame?

A. Alkanes
B. Alkenes
C. Alkynes
D. Unsaturated hydrocarbons

✅ Correct Answer: D. Unsaturated hydrocarbons

• Unsaturated hydrocarbons (alkenes/alkynes) have higher C:H ratio → incomplete combustion → sooty flame.

Q27. Which product is formed when methane undergoes complete combustion?

A. CO
B. CO₂ + H₂O
C. C + H₂O
D. CO₂ + H₂

✅ Correct Answer: B. CO₂ + H₂O

• CH₄ + 2O₂ → CO₂ + 2H₂O + heat.

Q28. The reaction of alcohols with sodium liberates:

A. Oxygen
B. Hydrogen
C. Carbon dioxide
D. Methane

✅ Correct Answer: B. Hydrogen

• 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑.

Q29. Which gas is formed when ethanol reacts with sodium?

A. Oxygen
B. Carbon dioxide
C. Hydrogen
D. Ethene

✅ Correct Answer: C. Hydrogen

Q30. Ethanol when heated with concentrated H₂SO₄ at 170°C produces:

A. Ethanoic acid
B. Ethene
C. Methane
D. Acetaldehyde

✅ Correct Answer: B. Ethene

• Dehydration reaction: C₂H₅OH → C₂H₄ + H₂O.

Q31. Which of the following is NOT an oxidation reaction?

A. Alcohol → Acid
B. Alkene → Diol
C. Alkane → Alkene
D. CO → CO₂

✅ Correct Answer: C. Alkane → Alkene

• This is dehydrogenation, not oxidation.

Q32. Oxidation of ethanol in presence of alkaline KMnO₄ gives:

A. Ethene
B. Methane
C. Ethanoic acid
D. Formaldehyde

✅ Correct Answer: C. Ethanoic acid

Q33. Which reaction is shown by alkanes?

A. Addition
B. Substitution
C. Neutralization
D. Esterification

✅ Correct Answer: B. Substitution

• Example: CH₄ + Cl₂ → CH₃Cl + HCl.

Q34. Which reaction is shown by alkenes and alkynes?

A. Substitution
B. Addition
C. Neutralization
D. Oxidation only

✅ Correct Answer: B. Addition

• Unsaturated hydrocarbons show addition of H₂, halogens etc.

Q35. Which reaction is responsible for turning vegetable oil into vegetable ghee?

A. Substitution
B. Oxidation
C. Hydrogenation
D. Saponification

✅ Correct Answer: C. Hydrogenation

• Addition of hydrogen to unsaturated oils in presence of Ni catalyst → saturated fats.

Q36. Which catalyst is used in the hydrogenation of oils?

A. Pt or Pd
B. Ni
C. Fe
D. MnO₂

✅ Correct Answer: B. Ni

• Finely divided nickel acts as catalyst.

Q37. The reaction of alcohol with carboxylic acid in presence of conc. H₂SO₄ is called:

A. Neutralization
B. Esterification
C. Hydrogenation
D. Saponification

✅ Correct Answer: B. Esterification

• Ethanol + Ethanoic acid → Ester + Water.

Q38. The fruity smell in esterification reaction is due to:

A. Alcohol
B. Acid
C. Ester
D. Hydrogen

✅ Correct Answer: C. Ester

Q39. Which acid is present in vinegar?

A. Formic acid
B. Acetic acid (Ethanoic acid)
C. Citric acid
D. Oxalic acid

✅ Correct Answer: B. Acetic acid (Ethanoic acid)

Q40. The reaction between an ester and NaOH is called:

A. Neutralization
B. Esterification
C. Saponification
D. Substitution

✅ Correct Answer: C. Saponification

• Ester + NaOH → Sodium salt of acid (soap) + Alcohol.

Q41. Ethanoic acid reacts with sodium carbonate to produce:

A. CO₂
B. H₂
C. O₂
D. CH₄

✅ Correct Answer: A. CO₂

• 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂↑.

Q42. The reaction of ethanoic acid with sodium bicarbonate releases:

A. Oxygen
B. Hydrogen
C. Carbon dioxide
D. Methane

✅ Correct Answer: C. Carbon dioxide

Q43. Which of these will give brisk effervescence with sodium carbonate?

A. Alcohol
B. Carboxylic acid
C. Ester
D. Ketone

✅ Correct Answer: B. Carboxylic acid

• Acids react with carbonates → CO₂ effervescence.

Q44. Common name of ethanoic acid is:

A. Vinegar
B. Lactic acid
C. Tartaric acid
D. Formic acid

✅ Correct Answer: A. Vinegar

Q45. Which of the following statements about soaps is FALSE?

A. Soaps are sodium salts of fatty acids
B. Soaps form lather in hard water
C. Soaps are biodegradable
D. Soaps are used for cleaning

✅ Correct Answer: B. Soaps form lather in hard water

• They do not form lather in hard water due to Ca²⁺, Mg²⁺ salts.

Q46. Ethanol is used in:

A. Medicines
B. Alcoholic drinks
C. Fuels (as biofuel)
D. All of these

✅ Correct Answer: D. All of these

Q47. Which statement about methanol is correct?

A. Safe for drinking
B. Causes blindness if consumed
C. Used in soft drinks
D. Harmless chemical

✅ Correct Answer: B. Causes blindness if consumed

Q48. What happens when ethanoic acid reacts with ethanol in presence of conc. H₂SO₄?

A. Soap is formed
B. Alcohol is formed
C. Ester is formed
D. Aldehyde is formed

✅ Correct Answer: C. Ester is formed

Q49. Which of the following is an oxidizing agent?

A. Conc. H₂SO₄
B. Alkaline KMnO₄
C. NaOH
D. HCl

✅ Correct Answer: B. Alkaline KMnO₄

• Strong oxidizing agent → converts alcohols to acids.

Q50. Which reaction is used to test for unsaturation in hydrocarbons?

A. Substitution with Cl₂
B. Addition of Br₂ (Bromine water test)
C. Oxidation with KMnO₄
D. Combustion

✅ Correct Answer: B. Addition of Br₂ (Bromine water test)

• Unsaturated hydrocarbons decolorize bromine water.

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