Alkanes - conformations, preparation, properties and halogenation — NEET & JEE Questions

Question 1 · difficulty L1 · recall

Rotation about the carbon-carbon single bond in ethane gives different

• A. conformations
• B. constitutional isomers
• C. functional groups
• D. oxidation states

Question 2 · difficulty L2 · understanding

Identify the correct IUPAC name of hydrocarbon $(x)$ containing three primary carbon atoms and with molar mass $72 \mathrm{~g} \mathrm{~mol}^{-1}$.

• A. 1, 1 - Dimethylcyclopropane
• B. 2, 2 - Dimethylpropane
• C. 2 - Methylbutane
• D. n-pentane

Question 3 · difficulty L2 · understanding

Given below are two statements : Statement (I) : Neopentane forms only one monosubstituted derivative. Statement (II) : Melting point of neopentane is higher than n-pentane. In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Statement I is incorrect but Statement II is correct
• B. Both Statement I and Statement II are correct
• C. Statement I is correct but Statement II is incorrect
• D. Both Statement I and Statement II are incorrect

Question 4 · difficulty L2 · understanding

In the given compound, the number of 2$$^\circ$$ carbon atom/s is ________.

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

Question 5 · difficulty L2 · understanding

The compound (X) on (i) on heating in the presence of anhydrous AlCl 3 and HCl gas gives 2,4-dimethyl pentane (ii) aromatization gives toluene and (iii) cyclisation gives methyl cyclohexane The correct name of compound (X) is:

• A. Hept-2-ene
• B. Hept-1,3,5-triene
• C. Heptane
• D. Hept-2,4,6-triene

Question 6 · difficulty L2 · understanding

Match the List - I with List - II List - I Name reaction List - II Product obtainable (A) Swarts reaction (I) Ethyl benzene (B) Sandmeyer's reaction (II) Ethyl iodide (C) Wurtz Fittig reaction (III) Cyanobenzene (D) Finkelstein reaction (IV) Ethyl fluoride Choose the correct answer from the options given below:

• A. A-II, B-III, C-I, D-IV
• B. A-II, B-I, C-III, D-IV
• C. A-IV, B-I, C-III, D-II
• D. A-IV, B-III, C-I, D-II

Question 7 · difficulty L2 · understanding

$$\stackrel{\bullet}{\mathrm{Cl}}+\mathrm{CH}_{4} \rightarrow \mathrm{A}+\mathrm{B}$$ A and B in the above atmospheric reaction step are :

• A. $$\mathrm{C}_{2} \mathrm{H}_{6}$$ and $$\mathrm{Cl}_{2}$$
• B. $$\stackrel{\bullet}{\mathrm{C}} \mathrm{HCl}_{2}$$ and $$\mathrm{H}_{2}$$
• C. $$\stackrel{\bullet}{\mathrm{C}}\mathrm{H}_{3}$$ and $$\mathrm{HCl}$$
• D. $$\mathrm{C}_{2} \mathrm{H}_{6}$$ and $$\mathrm{HCl}$$

Question 8 · difficulty L2 · understanding

Given below are two statements : Statement I : 2-methylbutane on oxidation with KMnO 4 gives 2-methylbutan-2-ol. Statement II : n-alkanes can be easily oxidised to corresponding alcohols with KMnO 4 . Choose the correct option :

• A. Both statement I and statement II are incorrect
• B. Both statement I and statement II are correct
• C. Statement I is correct but statement II is incorrect
• D. Statement I is incorrect but statement II is correct

Question 9 · difficulty L2 · understanding

One mole of an alkane (x) requires 8 mole oxygen for complete combustion. Sum of number of carbon and hydrogen atoms in the alkane (x) is ________.

Question 10 · difficulty L3 · understanding

Given below are two statements : Statement I : Methane can be prepared by decarboxylation of sodium ethanoate, Kolbe's electrolysis of sodium acetate and reaction of $\mathrm{CH}_3 \mathrm{MgBr}$ with water. Statement II : Methane cannot be prepared from unsaturated hydrocarbons and by Wurtz reaction. In the light of the above statements, choose the correct answer from the options given below

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true