Chapter 23

The number of optical isomers formed by hydrogenation of the compound, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CHCH}_{3}\) are (a) 0 (b) 1 (c) 2 (d) 3

The number and type of bonds between two carbon atoms in \(\mathrm{CaC}_{2}\) are (a) one sigma and one \(\pi\) bond (b) one sigma and two \(\pi\) bonds (c) one sigma and one and a half \(\pi\) bonds (d) one sigma bond

Which of the following has the least hindered rotation about carbon-carbon bond? (a) ethane (b) ethylene (c) acetylene (d) hexachloroethane

The \(\mathrm{Cl}-\mathrm{C}-\mathrm{Cl}\) angle in \(1,1,2,2\)-tetrachloroethene and tetrachloromethane will be about (a) \(120^{\circ}\) and \(109.5^{\circ}\) (b) \(90^{\circ}\) and \(109.5^{\circ}\) (c) \(109.5^{\circ}\) and \(90^{\circ}\) (d) \(109.5^{\circ}\) and \(120^{\circ}\)

The compound with an isopropyl group is (a) \(2,2,3,3\)-tetramethylpentane (b) 2,2 -dimethylpentane (c) \(2,2,3\)-trimethylpentane (d) 2-methylpentane

The enolic form of acetone contains (a) 9 sigma bonds, 1 pi bond and 2 lone pair of electrons (b) 8 sigma bonds, 2 pi bonds and 2 lone pair of electrons (c) 10 sigma bonds, 1 pi bond and 1 lone pair of electrons (d) 9 sigma bonds, 2 pi bonds and 1 lone pair of electrons

How many chiral carbon atoms are present in 2,3 , 4-trichloropentane? (a) three (b) two (c) one (d) four

The IUPAC name of (a) butan-2-aldehyde (b) 2-methylbutanal (c) 3 -methylisobutyraldehyde (d) 3-methylbutanal

An optically active compound is (a) 1-bromobutane (b) \(\beta\)-bromobutyric acid (c) 2-bromo-2-methylpropane (d) 1 -bromo-2-methylpropane

Which of the following compounds exhibit steroisomerism? (a) 2 -methylbutene-1 (b) 3 -methylbutyne-l (c) 3-methylbutanoic acid (d) 2-methylbutanoic acid

The number of isomers for the compound with molecular formula \(\mathrm{C}_{2} \mathrm{BrClFI}\) is (a) 3 (b) 4 (c) 5 (d) 6

Which of the following compounds will exhibit geometrical isomerism? (a) 1 -phenyl-2-butene (b) 3 -phenyl-1-butene (c) 2 -phenyl-1-butene (d) 1,1 -diphenyl-1-propene

Which of the following compounds will show geometrical isomerism? 1\. 2-butene 2\. propene 3\. 1-phenylpropene 4\. 2 -methylbut-2-ene (a) 1,2 (b) 3,4 (c) \(1,2,3\) (d) 1,3

How many optically active stereoisomers are possible for butan-2, 3 -diol? (a) 1 (b) 2 (c) 3 (d) 4

The number of possible enantiomeric pairs than can be produced during monochlorination of 2-methyl butane is (a) 2 (b) 3 (c) 4 (d) 1

Which is true regarding the \(\mathrm{HOCH}_{2}-(\mathrm{CHOH})_{4}\) \(-\mathrm{CH}_{2} \mathrm{OH} ?\) (1) the number of racemic mixtures will be four for the compound. (2) the total number of optical isomers is ten and number of meso isomer is two. (3) the total number of optical isomer is sixteen and number of meso isomer is zero. (4) the optically active isomers are eight while meso isomers are two. (a) 1,2 and 3 (b) 2,3 and 4 (c) 1,2 and 4 (d) 1 and 2 only

Match the following: List I List II 1\. \(\mathrm{CH}_{3} \mathrm{COOH}\) and \(\mathrm{HCOOCH}_{3}\) (i) metamers 2\. \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{C} \equiv \mathrm{CH}\) and (ii) position isomers \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_{3}\) 3\. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\) and (iii) tautomers \(\mathrm{CH}_{3}-\mathrm{CH}\left(\mathrm{NH}_{2}\right)-\mathrm{CH}_{3}\) 4\. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) and \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{O}\) (iv) functional isomer 1 2 3 4 (a) (iii) (iv) (i) (iv) (b) (i) (ii) (iii) (iv) (c) (iii) (ii) (i) (iv) (d) (iv) (ii) (ii) (iv)

Consider the following statements: (1) racemic forms are not optically active but are resolvable (2) the presence of chiral atom is sufficient but not the necessary condition for enantiomer (3) meso compounds are inactive and are not resolvable (4) conformational enantiomers can be resolved Now select the correct statements. (a) 1,2 and 3 (b) 2,3 and 4 (c) 1,2 and 4 (d) \(1,2,3\) and 4

How many structural and geometrical isomers are possible for dimethyl cyclohexane? (a) 3,3 (b) 3,6 (c) 6,6 (d) 6,3

Consider the following statements about chirality: 1\. molecules which are not superimposable on their mirror images are achiral 2\. a chiral molecule can have simple axis of symmetry 3\. a carbon atom to which four different species are attached is a chiral centre. 4\. a compound whose molecules are achiral exhibits optical activity Which of the statements given above are correct? (a) 1,2 and 4 (b) 2,3 and 4 (c) 2 and 3 (d) 1 and 4

Which of the following have asymmetric carbon atoms? 1\. \(\mathrm{ClCH}_{2}-\mathrm{CH}_{2} \mathrm{Br}\) 2\. \(\mathrm{CH}_{3}-\mathrm{CHCl}_{2}\) 3\. \(\mathrm{CH}_{3}-\mathrm{CH} \mathrm{DCl}\) 4\. \(\mathrm{CH}_{2} \mathrm{Br}-\mathrm{CHOH}-\mathrm{CH}_{3}\) (a) \(1,2,3\) (b) \(1,3,4\) (c) 2,3 (d) 3,4

Identify the correct statements (a) The stereisomers which are not mirror images are diastereomers. (b) Diasteteomers have the same physical properties like melting point and solubility (c) Cis isomer has higher melting point and lower solubility than the corresponding trans isomer (d) \(\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{COCH}_{3}\) exists more in enolic form in gaseous phase or in n- hexane.

For each category of compounds the minimum number of carbons required for optical isomerism to be possible is given. Find the correct match (es). (a) Alkane - 7 (b) Alkene \(-6\) (c) Alkyl halide - 4 (d) Alkadiene - 7

Which of the following are incorrect statements? (a) IUPAC names of succinic acid is ethane 1, 2-dicarbolxylic acid. (b) Enantiomorphs possess identical biological properties. (c) Tetrahydrofuran is a heteroaromatic compound (d) Generally homologues are not isomers.

Which of the following can show geometrical isomerism ? (a) But - 1- ene (b) But - 2- ene (c) Hex -3- ene (d) 2- Chlorobut -2- ene

A compound having molecular formula \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}\) can show (a) Functional isomerism (b) Metamerism (c) Position isomerism (d) Optical isomerism

Tautomerism and resonance are two different phenomena. In tautomerism, two structural isomers differing in the relative positions of their atoms are spontaneously interconvertible and can exist in dynamic equilibrium. The interconvertibility of tautomers involves making and breaking of bonds. In resonance, two or more structures are written for the same compound as each structure could not explain all the properties of the compound. The resonating or canonical structures do not differ in the position of atoms but only bonds and unpaired electrons have different positions in the different structures. The actual structure of the compound is the hybrid of the canonical structures. Enol content of \(\mathrm{CH}_{3}-\mathrm{CO}-\mathrm{CH}_{2}-\mathrm{CO}-\mathrm{CH}_{3}\) will be maximum in which of the solvents? (a) Water (b) \(\mathrm{n}\) - hexane (c) \(\mathrm{CH}_{3}-\mathrm{COOH}\) (d) Aqueous \(\mathrm{HCl}\)

$$ \begin{aligned} &\text { Match the following }\\\ &\begin{array}{ll} \hline \text { Column-I } & \text { Column-II } \\ \hline \text { (a) Enantiomers } & \text { (p) Equilibrium mixture } \\ \text { (b) Diastereomers } & \text { (q) Mirror images } \\ \text { (c) Meso isomer } & \text { (r) Non- mirror images } \\ \text { (d) Tautomers } & \text { (s) Non- superimposable } \\ & \text { (t) Stereo isomer } \\ \hline \end{array} \end{aligned} $$

Match the following Column-I (a) \(\mathrm{CH}_{3} \mathrm{CHDT}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}(\mathrm{OH}) \mathrm{C}_{2} \mathrm{H}_{5}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{3}\) (d) Column-II (p) No optical isomer (q) Two optical isomers (r) Four optical isomers (s) Three optical isomers (t) Two asymmetric carbon atoms.

In the following questions two statements (Assertion) (A) and Reason (R) are given. Mark (a) If both \(\mathrm{A}\) and \(\mathrm{R}\) are correct and \(\mathrm{R}\) is the correct explanation of \(\mathrm{A}\). (b) If both A and \(R\) are correct but \(R\) is not the correct expalnation of \(\mathrm{A}\). (c) \(\mathrm{A}\) is true but \(\mathrm{R}\) is false. (d) \(\mathrm{A}\) is false but \(\mathrm{R}\) is true. (e) \(\mathrm{A}\) and \(\mathrm{R}\) both are false. (Assertion): The reaction of \(\mathrm{HCN}\) with \(\mathrm{EtCH}(\mathrm{Me})\) \(\mathrm{C}^{13} \mathrm{HO}\) gives two optically active isomers in unequal amounts. (Reason): Formation of cyanohydrins at \(\mathrm{C}-13\) gives rise to \(\mathrm{d}\) and 1 isomers.

In the following questions two statements (Assertion) (A) and Reason (R) are given. Mark (a) If both \(\mathrm{A}\) and \(\mathrm{R}\) are correct and \(\mathrm{R}\) is the correct explanation of \(\mathrm{A}\). (b) If both A and \(R\) are correct but \(R\) is not the correct expalnation of \(\mathrm{A}\). (c) \(\mathrm{A}\) is true but \(\mathrm{R}\) is false. (d) \(\mathrm{A}\) is false but \(\mathrm{R}\) is true. (e) \(\mathrm{A}\) and \(\mathrm{R}\) both are false. (Assertion): An optically active molecule must be asymmetric. (Reason): Asymmetric molecules will have nonsuperposable mirror image.

The total number of optically active isomers of the compound \(\mathrm{CH}_{2} \mathrm{OH}-\mathrm{CHBr}-\mathrm{CHOH}-\mathrm{CHBr}-\mathrm{CH}_{2} \mathrm{OH}\) is _________________

The number of isomeric ethers corresponding to the formula \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}\) is _____________

Number of mesoforms possible for the compound \(\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CHCl}-\mathrm{CHCl}-\mathrm{CHCl}-\mathrm{CHCl}-\mathrm{C}_{6} \mathrm{H}_{5}\) is

The number of geometrical isomers of the following alkene \(\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}-\mathrm{Cl}\) is

Find out the total number of isomeric molecules form on dichlorination of cyclopentane/

How many structural isomers are possible for monobromodichloro benzene?

Racemic mixture is formed by mixing two (a) isomeric compounds (b) chiral compounds (c) meso compounds (d) enantiomers with chiral carbon

A similarly between optical and geometrical isomerism is that (a) if in a compound, one is present then so is the other. (b) each forms equal number of isomers for a given compound (c) both are included in stereoisomerism (d) they have no similarly

Which of the following does not show geometrical isomerism? (a) 1,1 -dichloro-1-pentene (b) 1,2 -dichloro- 1 -pentene (c) 1,3 -dichloro-1-pentene (d) 1,4 -dichlroro-2-pentene

The IUPAC name of \(\mathrm{CH}_{3} \mathrm{COCH}\left(\mathrm{CH}_{3}\right)_{2}\) is (a) 4 -methyl isopropyl ketone (b) 3 -methylbutan-2-one (c) isopropylmethyl ketone (d) 2 -methylbutan-3-one

The IUPAC name of the following compound is [2004] CC1(C)CCCC(O)C1 (a) 3,3 -dimethyl-1-hydroxycyclohexane (b) 1,1 -dimethyl-3-hydroxycyclohexane (c) 3,3 -dimethyl-1-cyclohexanol (d) 1,1 -dimethyl-3-cyclohexanol.

Which one of the following does not have sp² hybridized carbon? (a) acetone (b) acetic acid (c) acetonitrile (d) acetamide

Which of the following will have a meso isomer also? [2004] (a) 2-chlorobutane (b) 2,3 -dichlorobutane (c) 2,3 -dichloropentane (d) 2-hydroxypropanoic acid

For which of the following parameters of the structural isomers \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) and \(\mathrm{CH}_{3} \mathrm{OCH}_{3}\) would be expected to have the same values? (Assume ideal behaviour)[2004] (a) heat of vaporization (b) vapour pressure at the same temperature (c) boiling points (d) gaseous densities at the same temperature and pressure

Of the five isomeric hexanes, the isomer which can give two monochlorination compound is [2005] (a) n-hexane (b) 2,3 -dimethylbutane (c) 2,2 -dimethylbutane (d) 2-methylpentane

Which types of isomerism is shown by 2,3 -dichlorobutane? (a) diastereo (b) optical (c) geometric (d) structural

Which one of the following conformations of cyclohexane is chiral? (a) rigid (b) chair (c) boat (d) twist boat

The IUPAC name of CCC(CC)C(C)(C)CC is (a) 4,4 - dimethyl-5-diethyl pentane (b) 5,5 -diethyl-4, 4-dimethyl pentane (c) 3 -ethyl-4, 4-dimethyl heptane (d) 1,1 -diethyl-2, 2 -dimethyl pentane

The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is (a) \(-\mathrm{COOH},-\mathrm{SO}_{3} \mathrm{H},-\mathrm{CONH}_{2},-\mathrm{CHO}\) (b) \(-\mathrm{SO}_{3} \mathrm{H},-\mathrm{COOH},-\mathrm{CONH}_{2},-\mathrm{CHO}\) (c) \(-\mathrm{CHO},-\mathrm{COOH},-\mathrm{SO}_{3} \mathrm{H},-\mathrm{CONH}_{2}\) (d) \(-\mathrm{CONH}_{2},-\mathrm{CHO},-\mathrm{SO}_{3} \mathrm{H},-\mathrm{COOH}\)