Free Chemistry of Hydrocarbons MCQs with Answers

• A. 1-Butyne
• B. 2-Butyne
• C. 2-Pentyne
• D. 3-Hexyne

Explanation: 1-Butyne has a terminal triple bond, so it can exhibit acidic properties.

• A. 1, 5 - Hexadiyne - 3 - ene
• B. 1, 5 - Hexadiene 3 - yne
• C. 3 - Hexene - 1,5 - diyne
• D. 3 - Hexyne - 1 , 5 - diene

Explanation: This is consistent with option B. Note: - is used to separate words from numbers.

• A. Addition reaction
• B. Elimination reaction
• C. Substitution reaction
• D. Halogenation

Explanation: Alkynes undergo addition reactions across the triple bond because of their weak pi-bonds between carbon atoms, which are converted into…

• A. Acidic
• B. Basic
• C. Neutral
• D. None

Explanation: Alkynes are slightly acidic in nature due to the presence of a hydrogen atom attached to a highly electronegative carbon-carbon triple…

• A. Propanal
• B. Propyl hydrogen sulfate
• C. Acetone
• D. Propanol

Explanation: When propyne is treated with acidified HgSO4, the major product formed is acetone (Propanone).

• A. Acetic acid
• B. Ethyl alcohol
• C. Oxalic acid
• D. Ethylene glycol

Explanation: The end product of the oxidation of ethyne is Oxalic acid. When ethyne undergoes oxidation, it first forms Glyoxal, which then further…

• A. O2
• B. Br2
• C. NaNH2
• D. HCl

Explanation: The correct answer is Option C: NaNH2. 1-Butyne and 2-butyne can be differentiated using NaNH2 due to the reactivity of terminal hydrogen.

• A. AlCl3
• B. HNO3
• C. BeCl2
• D. NaCl

Explanation: Aluminium trichloride (AlCl3) is often used as a catalyst in Friedel-Crafts reactions since it acts as a Lewis acid and coordinates with…

• A. NO3
• B. NO+2
• C. NO2
• D. HNO3

Explanation: Nitration of benzene: Nitric acid and sulfuric acid used in nitration generate nitronium NO2+ ions as electrophiles.

• A. H2SO4
• B. HSO4
• C. SO+3
• D. SO3

Explanation: Sulfur trioxide or its protonated derivative is the actual electrophile in this electrophilic aromatic substitution.

• A. Low
• B. High
• C. Equal
• D. None

Explanation: hydrogen:carbon monoxide ratio of approximately 2:1 is required for hydrocarbon production. The by-product is water.

• A. One
• B. Two
• C. Three
• D. Four

Explanation: When 1 more substituent is introduced.(I) will give 3 isomeric products, ortho, meta and para disubstituted benzenes.(II) will produce…

• A. Vapour density method
• B. X-ray diffraction
• C. Elemental analysis
• D. Degradation method

Explanation: Benzene has a molecular weight, based on the formula of C6H6, of 78.1 amu's.

• A. 0.99 Å
• B. 1.09 Å
• C. 1.12 Å
• D. 1.397 Å

Explanation: Carbon-hydrogen bonds have a bond length of about 1.09 Å (1.09 × 10−10 m) and a bond energy of about 413 kJ/mol (see table below).

• A. sp
• B. sp2
• C. sp3
• D. None of these

Explanation: Each carbon in benzene is sp2 hybridised because each carbon atom is attached to 2 other carbon atoms and 1 Hydrogen atom and has no lone…

• A. 358.5 kJ/mole
• B. 119 kJ-mol-1
• C. 208 kJ-mol-1
• D. 150.5 kJ-mol-1

Explanation: Benzene has three double bonds, so we might expect its heat of hydrogenation to be -360 kJ/mol.

• A. Ni/200oC
• B. V2O5/450oC
• C. AlCl3/150oC
• D. Sunlight

Explanation: The oxidation of benzene by V2O5 in the presence of air produces maleic anhydride. The oxidation is carried out at 500 oC.

• A. Petroleum
• B. Coal-tar
• C. Living organism
• D. Dead marine animals

Explanation: Aromatic compounds are cyclic compounds in which all ring atoms participate in a network of π bonds, resulting in unusual stability.

• A. Benzene
• B. Thiophene
• C. Divinyl acetylene
• D. Xylene

Explanation: Acetylene on passing through red hot iron tube at 873K undergoes cyclic polymerization.

• A. CHO
• B. -SO3H
• C. -NO2
• D. Cl

Explanation: Chlorine withdraws electrons through inductive effect and releases electrons through resonance.