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Chapter 13: Hydrocarbons

NCERT Solutions for CBSE Class 10 Chemistry — 18 solved questions with detailed explanations.

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Solved Questions

Q1. The general formula of alkynes is:

CₙH₂ₙ
CₙH₂ₙ₋₂
CₙH₂ₙ₊₂
CₙHₙ

Difficulty: Easy · Topic: General Formulas

Solution

Alkynes: CₙH₂ₙ⁻₂. They have one triple bond (C≡C).

Q2. Alkanes have the general formula:

CₙH₂ₙ
CₙH₂ₙ₋₂
CₙHₙ
CₙH₂ₙ₊₂

Difficulty: Easy · Topic: Hydrocarbons

Solution

CₙH₂ₙ₊₂.

Q3. Alkenes have the general formula:

CₙH₂ₙ₋₂
CₙH₂ₙ₊₂
CₙHₙ
CₙH₂ₙ

Difficulty: Easy · Topic: Hydrocarbons

Solution

CₙH₂ₙ.

Q4. Baeyer's test uses:

neutral KMnO₄
acidic KMnO₄
K₂Cr₂O₇
alkaline KMnO₄

Difficulty: Easy · Topic: Hydrocarbons

Solution

alkaline KMnO₄.

Q5. Ozonolysis of alkenes produces:

alcohols
aldehydes/ketones
amines
acids

Difficulty: Easy · Topic: Hydrocarbons

Solution

aldehydes/ketones.

Q6. Lindlar's catalyst converts alkyne to:

cis-alkene
alkane
alcohol
trans-alkene

Difficulty: Easy · Topic: Hydrocarbons

Solution

cis-alkene.

Q7. Birch reduction of benzene gives:

cyclohexene
toluene
1,4-cyclohexadiene
cyclohexane

Difficulty: Easy · Topic: Hydrocarbons

Solution

1,4-cyclohexadiene.

Q8. Benzene undergoes electrophilic substitution rather than addition because:

It has weak π bonds
It gains resonance stabilization
It has strong σ bonds
It is a weak electrophile

Difficulty: Easy-Medium · Topic: Aromatic Chemistry

Solution

Benzene's aromatic stabilization (36 kcal/mol resonance energy) is preserved in substitution but lost in addition.

Q9. Wurtz reaction is used to prepare:

Alkenes
Alkynes
Higher alkanes
Alcohols

Difficulty: Easy-Medium · Topic: Organic Reactions

Solution

Wurtz reaction: 2RX + 2Na → R-R + 2NaX. Used to prepare symmetrical higher alkanes.

Q10. Wurtz reaction involves:

esterification
dehydration
polymerization
R-X + Na → R-R (higher alkane)

Difficulty: Easy-Medium · Topic: Named Reactions

Solution

Wurtz reaction: R-X + Na → R-R (higher alkane).

Q11. Friedel-Crafts alkylation involves:

Electrophilic substitution with R-X/AlCl₃
addition
reduction
elimination

Difficulty: Easy-Medium · Topic: Named Reactions

Solution

Friedel-Crafts alkylation: Electrophilic substitution with R-X/AlCl₃.

Q12. IUPAC name of CH₃CH₂CH₃:

Propane
Ethane
Pentane
Butane

Difficulty: Easy-Medium · Topic: IUPAC

Solution

CH₃CH₂CH₃ = Propane.

Q13. IUPAC name of CH₃CH(CH₃)CH₂CH₃:

Pentane
3-Methylbutane
2-Ethylpropane
2-Methylbutane

Difficulty: Easy-Medium · Topic: IUPAC

Solution

CH₃CH(CH₃)CH₂CH₃ = 2-Methylbutane.

Q14. IUPAC name of CH₂=CH₂:

Propene
Ethene
Ethyne
Ethane

Difficulty: Easy-Medium · Topic: IUPAC

Solution

CH₂=CH₂ = Ethene.

Q15. IUPAC name of CH≡CH:

Ethene
Ethyne
Ethane
Propyne

Difficulty: Easy-Medium · Topic: IUPAC

Solution

CH≡CH = Ethyne.

Q16. Number of structural isomers of C₄H₁₀ (butane):

2
1
3
4

Difficulty: Medium · Topic: Isomerism

Solution

C₄H₁₀ (butane) has 2 structural isomers.

Q17. Number of structural isomers of C₅H₁₂ (pentane):

4
3
5
2

Difficulty: Medium · Topic: Isomerism

Solution

C₅H₁₂ (pentane) has 3 structural isomers.

Q18. Number of structural isomers of C₆H₁₄ (hexane):

5
3
4
6

Difficulty: Medium · Topic: Isomerism

Solution

C₆H₁₄ (hexane) has 5 structural isomers.

Other Chapters in Chemistry

Ch 1: Some Basic Concepts Ch 2: Structure of Atom Ch 3: Classification of Elements Ch 4: Chemical Bonding Ch 5: States of Matter Ch 6: Thermodynamics Ch 7: Equilibrium Ch 8: Redox Reactions Ch 9: Hydrogen Ch 10: s-Block Elements Ch 11: p-Block Elements Ch 12: Organic Chemistry Ch 14: Environmental Chemistry

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