Chapter 13

In the following skew conformation of ethane, \(\mathrm{H}^{\prime}-\mathrm{C}-\mathrm{C}-\mathrm{H}_{3}\) dihedral angle is : [Main April 12, 2019 (II)] CC(C)C (a) \(58^{\circ}\) (b) \(149^{\circ}\) (c) \(151^{\circ}\) (d) \(120^{\circ}\)

Which of the following compounds shows geometrical isomerism? \(\quad\) [Main Sep. 06, 2020 (I)] (a) 2-methylpent-2-ene (b) 4-methylpent-2-ene (c) 4-methylpent-1-ene (d) 2-methylpent-1-ene

The increasing order of the reactivity of the following compounds towards electrophilic aromatic substitution reactions is : [Main April 10, 2019 (I)] Clc1ccccc1 Cc1ccccc1 CC(=O)c1ccccc1 \((\mathrm{I}\) (II (a) II < I

At \(300 \mathrm{~K}\) and 1 atmospheric pressure, \(10 \mathrm{~mL}\) of a hydrocarbon required \(55 \mathrm{~mL}\) of \(\mathrm{O}_{2}\) for complete combustion, and \(40 \mathrm{~mL}\) of \(\mathrm{CO}_{2}\) is formed. The formula of the hydrocarbon is: [Main April 10, 2019 (I)] (a) \(\mathrm{C}_{4} \mathrm{H}_{10}\) (b) \(\mathrm{C}_{4} \mathrm{H}_{6}\) (c) \(\mathrm{C}_{4} \mathrm{H}_{7} \mathrm{Cl}\) (d) \(\mathrm{C}_{4} \mathrm{H}_{8}\)

The major product obtained in the photo catalysed bromination of 2 methylbutane is: [Main 2005, Online May 19, 2012; Online April 12, 2014] (a) 1-bromo-2-methylbutane (b) 1-bromo-3-methylbutane (c) 2-bromo-3-methylbutane (d) 2-bromo-2-methylbutane

The major product formed in the following reaction is : \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}\left(\mathrm{CH}_{3}\right)_{2} \stackrel{\mathrm{HBr}}{\longrightarrow}\) [Main Sep. 05, 2020 (II)] (a) \(\mathrm{CH}_{3} \mathrm{CH}(\mathrm{Br}) \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{Br}) \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}\) (c) \(\mathrm{Br}\left(\mathrm{CH}_{2}\right)_{3} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C}(\mathrm{Br})\left(\mathrm{CH}_{3}\right)_{2}\)

When 2-butyne is treated with \(\mathrm{H}_{2} /\) Lindlar's catalyst, compound \(\mathrm{X}\) is produced as the major product and when treated with \(\mathrm{Na} / \mathrm{liq} . \mathrm{NH}_{3}\) it produces \(\mathrm{Y}\) as the major product. Which of the following statements is correct? [Main Online April 15, \(\mathbf{2 0 1 8}\) (II)] (a) Y will have higher dipole moment and higher boiling point than \(\mathrm{X}\) (b) Y will have higher dipole moment and lower boiling point than \(\mathrm{X}\) (c) \(\mathrm{X}\) will have lower dipole moment and lower boiling point than \(\mathrm{Y}\) (d) \(\mathrm{X}\) will have higher dipole moment and higher boiling point than \(\mathrm{Y}\)

In the following sequence of reactions : Toluene \(\stackrel{\mathrm{KMnO}_{4}}{\longrightarrow} \mathrm{A} \stackrel{\mathrm{SOCl}_{2}}{\longrightarrow} \mathrm{B} \frac{\mathrm{II}_{2} / \mathrm{Pd}}{\mathrm{BaSO}_{4}} \mathrm{C}\) (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{OH}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHO}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{3}\)

The bond energy (in kcal \(\mathbf{m o l}^{-1}\) ) of a \(\mathrm{C}-\mathrm{C}\) single bond is approximately [2010] (a) 1 (b) 10 (c) 100 (d) 1000

The synthesis of 3-octyne is achieved by adding a bromoalkane into a mixture of sodium amide and an alkyne. The bromoalkane and alkyne respectively are [2010] (a) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) and \(\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}\) (b) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) and \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}\) (c) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) and \(\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CH}\) (d) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) and \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}\)

On monochlorination of 2 -methylbutane, the total number of chiral compounds formed is [2004S] (a) 2 (b) 4 (c) 6 (d) 8

Which of the following is used for the conversion of2-hexyne into trans-2-hexene? (a) \(\mathrm{H}_{2} / \mathrm{Pd} / \mathrm{BaSO}_{4}\) (b) \(\mathrm{H}_{2}, \mathrm{PtO}_{2}\) (c) \(\mathrm{NaBH}_{4}\) (d) \(\mathrm{Li}-\mathrm{NH}_{3} / \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\)

Which of the following compounds does not dissolve in conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) even on warming? [1983 - 1 Mark] (a) ethylene (b) benzene (c) hexane (d) aniline

Which of the following has the shortest \(\mathrm{C}-\mathrm{Cl}\) bond? [Main Jan. 09, 2020 (II)] (a) \(\mathrm{Cl}-\mathrm{CH}=\mathrm{CH}_{2}\) (b) \(\mathrm{Cl}-\mathrm{CH}=\mathrm{CH}-\mathrm{NO}_{2}\) (c) \(\mathrm{Cl}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{3}\) (d) \(\mathrm{Cl}-\mathrm{CH}=\mathrm{CH}-\mathrm{OCH}_{3}\)

$$ \mathrm{Ph}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_{3} \stackrel{\mathrm{Hg}^{2+} / \mathrm{H}^{+}}{\longrightarrow} A . A \text { is: } $$

Among the following, the compound that can be most readily sulphonated is [1982] (a) benzene (b) nitrobenzene (c) toluene (d) chlorobenzene

Identify the reagent from the following list which can easily distinguish between 1-butyne and 2-butyne [2002S] (a) bromine, \(\mathrm{CCl}_{4}\) (b) \(\mathrm{H}_{2}\), Lindlar catalyst (c) dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{HgSO}_{4}\) (d) ammonical \(\mathrm{Cu}_{2} \mathrm{Cl}_{2}\) solution

The bond order of individual carbon-carbon bonds in benzene is [1981] (a) one (b) two (c) between one and two (d) one and two, alternately

When cyclohexane is poured on water, it floats, because: (a) cyclohexane is in 'boat' form [1997-1 Mark] (b) cyclohexane is in 'chair' form (c) cyclohexane is in 'crown' form (d) cyclohexane is less dense than water.

Which of the following will have least hindered rotation about carbon-carbon bond? [1987-1 Mark] (a) Ethane (b) Ethylene (c) Acetylene (d) Hexachloroethane

Propyne and propene can be distinguished by (a) conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (b) \(\mathrm{Br}_{2}\) in \(\mathrm{CCl}_{4}\) (c) dil. \(\mathrm{KMnO}_{4}\) (d) \(\mathrm{AgNO}_{3}\) in ammonia

The compound with the highest boiling point is (a) \(n\)-hexane (b) \(n\)-pentane (c) 2,2 -dimethylpropane (d) 2-methylbutane

But 2-ene on reaction with alkaline \(\mathrm{KMnO}_{4}\) at elevated temperature followed by acidification will give : [Main April 12, 2019 (I)] (a) CC(O)C(C)O (b) one molecule of \(\mathrm{CH}_{3} \mathrm{CHO}\) and one molecule of \(\mathrm{CH}_{3} \mathrm{COOH}\) (c) 2 molecules of \(\mathrm{CH}_{3} \mathrm{COOH}\) (d) 2 molecules of \(\mathrm{CH}_{3} \mathrm{CHO}\)

The product(s) obtained via oxymercuration of 1 - butyne would be [1999-2 Marks] (a) CCC(C)=O (b) \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CHO}\) (c) \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CHO}+\mathrm{HCHO}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}+\mathrm{HCOOH}\)

Kolbe electrolysis of potassium succinate gives \(\mathrm{CO}_{2}\) and .......

Marsh gas mainly contains (a) \(\mathrm{C}_{2} \mathrm{H}_{2}\) (b) \(\mathrm{CH}_{4}\) (c) \(\mathrm{H}_{2} \mathrm{~S}\) (d) \(\mathrm{CO}\)

Acidic hydrogen is present in: (a) ethyne (b) ethene (c) benzene (d) ethane

................ ring is most strained. (Cyclopropane, Cyclobutane, Cyclopentane)

The trans-alkenes are formed by the reduction of alkynes with: [Main 2018] (a) \(\mathrm{H}_{2}-\mathrm{Pd} / \mathrm{C}, \mathrm{BaSO}_{4}\) (b) \(\mathrm{NaBH}_{4}\) (c) \(\mathrm{Na} / \mathrm{liq} . \mathrm{NH}_{3}\) (d) \(\mathrm{Sn}-\mathrm{HCl}\)

When propyne is treated with aqueous \(\mathrm{H}_{2} \mathrm{SO}_{4}\) in presence of \(\mathrm{HgSO}_{4}\) the major product is [1983-1 Mark| (a) propanal (b) propyl hydrogensulphate (c) acetone (d) propanol

3-Methyl-pent-2-ene on reaction with HBr in presence of peroxide forms an addition product. The number of possible stereoisomers for the product is: [Main 2017] (a) Six (b) Zero (c) Two (d) Four

Acetylene is treated with excess sodium in liquid ammonia. The product is reacted with excess methyl iodide. The final product is

The reaction of propene with HOCl \(\left(\mathrm{Cl}_{2}+\mathrm{H}_{2} \mathrm{O}\right)\) proceeds through the intermediate: [Main 2016] (a) \(\mathrm{CH}_{3}-\mathrm{CH}(\mathrm{OH})-\mathrm{CH}_{2}^{+}\) (b) \(\mathrm{CH}_{3}-\mathrm{CHCl}-\mathrm{CH}_{2}^{+}\) (c) \(\mathrm{CH}_{3}-\mathrm{CH}^{+}-\mathrm{CH}_{2}-\mathrm{OH}\) (d) \(\mathrm{CH}_{3}-\mathrm{CH}^{+}-\mathrm{CH}_{2}-\mathrm{Cl}\)

................ is most acidic. (Ethane, Ethene, Ethyne)

Toluene, when treated with \(\mathrm{Br}_{2} / \mathrm{Fe}\), gives \(p\)-bromotoluene as the major product because \(\mathrm{CH}_{3}\) group (a) is para directing [1999-3 Marks] (b) is meta directing (c) activates the ring by hyperconjugation (d) deactivates the ring

An aromatic molecule will (a) have \(4 n \pi\) electrons (b) have \((4 n+2) \pi\) electrons (c) be planar (d) be cyclic

In the hydroboration - oxidation reaction of propene with diborane, \(\mathrm{H}_{2} \mathrm{O}_{2}\) and \(\mathrm{NaOH}\), the organic compound formed is: (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) (b) \(\mathrm{CH}_{3} \mathrm{CHOHCH}_{3}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) (d) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}\)

Give reasons for the following : (i) tert-Butylbenzene does not give benzoic acid on treatment with acidic \(\mathrm{KMnO}_{4}\). [2000-1 Mark] (ii) Toluene reacts with bromine in the presence of light to give benzyl bromide while in presence of \(\mathrm{FeBr}_{3}\) it gives \(p\) bromotoluene. Give explanation for the above observations. [1996 - 2 Marks] (iii) Although benzene is highly unsaturated, normally it does not undergo addition reaction.[1983 - 1 Mark]

Optically active 2-iodobutane on treatment with NaI in acetone gives a product which does not show optical activity. Explain briefly.

The addition of HI in the presence of peroxide catalyst does not follow anti- Markovnikov's rule because : [Main Online April 9, 2013] (a) \(\mathrm{HI}\) is a strong reducing agent. (b) H-I bond is too strong to be broken homolytically. (c) I atom combines with \(\mathrm{H}\) atom to give back HI. (d) Iodine atom is not reactive enough to add across a double bond.

\(n\)-Butane is produced by the monobromination of ethane followed by the Wurtz reaction. Calculate the volume of ethane at NTP required to produce \(55 \mathrm{~g} n\)-butane, if the bromination takes place with 90 per cent yield and the Wurtz reaction with 85 per cent yield. [1989 - 3 Marks]

Give reason of the following : Methane does not react with chlorine in the dark.

In allene \(\left(\mathrm{C}_{3} \mathrm{H}_{4}\right)\), the type(s) of hybridisation of the carbon atoms is (are): [2012] (a) \(s p\) and \(s p^{3}\) (b) \(s p\) and \(s p^{2}\) (c) only \(s p^{3}\) (d) \(s p^{2}\) and \(s p^{3}\)

Give reason of the following : Normally, benzene gives electrophilic substitution reaction rather than electrophilic addition reaction although it has double bonds.

Arrange the following in : benzene, toluene, methoxybenzene, chlorobenzene in increasing order of reactivity towards sulphonation with fuming sulphuric acid.

Write down the heterogeneous catalyst involved in the polymerisation of ethylene.

Write down the reactions involved in the preparation of the following, using the reagents indicated against it in parenthesis. Ethylbenzene from benzene \(\left[\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, \mathrm{PCl}_{5}\right.\), anhydrous \(\left.\mathrm{AlCl}_{3}\right]\).

The nodal plane in the \(\pi\)-bond of ethene is located in (a) the molecular plane [2002S] (b) a plane parallel to the molecular plane (c) a plane perpendicular to the molecular plane which bisects the carbon carbon \(\sigma\)-bond at right angle (d) a plane perpendicular to the molecular plane which contains the carbon \- carbon \(\sigma\)-bond.

The reaction of propene with HOCl proceeds via the addition of [2001S] (a) \(\mathrm{H}^{+}\)in the first step (b) \(\mathrm{Cl}^{+}\)in the first step (c) \(\mathrm{OH}^{-}\)in the first step (d) \(\mathrm{Cl}^{+}\)and \(\mathrm{OH}^{-}\)in a single step

In the presence of peroxide, hydrogen chloride and hydrogen iodide do not give anti-Markovnikov addition to alkenes because [2001S] (a) both are highly ionic (b) one is oxidizing and the other is reducing (c) one of the steps is endothermic in both the cases (d) all the steps are exothermic in both the cases