Genius Science Academy

TEST PAPER: HYDROCARBONS

Time: 3 Hours | Marks: 100 | Date: 16/02/2026

Answer all questions. (1 mark each)

Define Hydrocarbons.
What is the general formula for Alkanes?
Why are alkanes called 'paraffins'?
State the hybridization of carbon atoms in Alkenes.
What is the C-C bond length in Alkanes?
Define 'Isomerism'.
What is the general formula for Alkynes?
Define 'Conformations'.
What is a 'Torsion angle'?
Name the parent compound of the entire family of aromatic compounds.
What is the common name for Alkenes?
Give the IUPAC name of the first member of the Alkyne series.
State Huckel’s Rule for aromaticity.
Which alkane is the major product in a Wurtz reaction using a mixture of alkyl halides?
What are 'Arenes'?
Name the catalyst used for the hydrogenation of ethene at room temperature.
Define 'Vicinal Dihalides'.
What is the geometry of a benzene molecule?
Name one ortho-para directing group.
Mention one meta-directing group.
What is the torsion angle in an 'eclipsed' conformation of ethane?
Which gas is produced during the complete combustion of alkanes?
Give the chemical formula for 'Sodium Ethynide'.
Define 'Torsional Energy'.
Name a known carcinogenic aromatic hydrocarbon.

Answer any 10 out of 12 questions. (2 marks each)

Differentiate between 'Cis' and 'Trans' isomers in alkenes.
Explain the 'Saytzeff's Rule' with an example.
How is benzene prepared from Ethyne? Give the reaction conditions.
State the physical properties of Alkanes regarding their solubility.
What is the 'Markovnikov’s Rule'?
Draw the structural isomers of Butane (C₄H₁₀).
Why is the staggered conformation of ethane more stable than the eclipsed form?
Mention any two characteristics of aromatic compounds.
Show the reaction for the preparation of ethane from Ethyl Bromide using Zinc and dil. HCl.
Explain the 'Peroxide effect' (Anti-Markovnikov addition) in alkenes.
Give the structural formula for Cyclobutane and Propane.
Why do branched-chain alkanes have lower boiling points than straight-chain alkanes?

Answer any 10 out of 14 questions. (3 marks each)

Describe the 'Wurtz Reaction' for the preparation of Alkanes.
Explain the 'Friedel-Crafts Alkylation' of benzene with a chemical equation.
Discuss the acidic nature of Alkynes compared to alkanes and alkenes.
Explain the 'Nitration' of benzene, including the reagents used.
Describe the preparation of Alkenes by the dehydration of alcohols.
Illustrate the 'Newman Projections' for the eclipsed and staggered conformations of ethane.
Write a note on the 'Pyrolysis' or 'Cracking' of alkanes.
Explain the 'Directive Influence' of the hydroxyl group (-OH) in benzene.
Describe the preparation of ethyne from Calcium Carbide.
What is 'Geometrical Isomerism'? Why is it exhibited by alkenes?
Give the step-by-step mechanism for the generation of a Nitronium ion (NO₂⁺) in benzene nitration.
Explain the 'Halogenation' of alkanes under UV light.
Discuss the 'Resonance' structure of Benzene.
Explain 'Ozonolysis' of Alkenes with a suitable example.

Answer any 5 out of 7 questions. (5 marks each)

Classify Hydrocarbons in detail with a flow chart and examples for each category.
Explain in detail using both Sawhorse and Newman projections. Discuss their relative stability.
Write chemical equations for: Hydrogenation, Halogenation, Hydrohalogenation, Hydration, and Hydroboration-Oxidation.
Explain the general mechanism of Electrophilic Substitution in benzene, including the formation of the sigma-complex.
Write the structures and IUPAC names of all five chain isomers of Hexane (C₆H₁₄).
Explain Hydration (addition of H₂O), Polymerization to form Benzene, and formation of metal alkynides.
Compare the directive influence and activating/deactivating effects of Ortho-Para directing groups versus Meta directing groups.