Consider the following nucleophilic groups : $\text{I. } -\mathrm{O}-\mathrm{SO}_2-\mathrm{C}_6 \mathrm{H}_5$ ${\text{II}}.\,\, - {\text{O}} - \mathop {\text{C}}\limits^{\begin{array}{*{20}{c}} {\text{O}} \\ {||} \end{array}} - {\text{C}}{{\text{H}}_3}$ $\text{III. }-{Cl}$ $\text{IV. }-\mathrm{OCH}_3$ What is the correct order of leaving power of the above nucleophilic substitution reaction?

$\text{I}>\text{III}>\text{II}>\text{IV}$

$\text{I}>\text{II}>\text{IV}>\text{III}$

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JEE • CHEMISTRY • ORGANIC CHEMISTRY-SOME BASIC PRINCIPLES AND TECHNIQUES

Organic chemistry-some basic principles and techniques practice · Medium

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151 Medium

151 of 195

Analyzing +4 | -1

Assertion: The IUPAC name of

HC \equiv C - C{H_2} - CH = C{H_2}

is pent-4-en-1-yne.

Reason: A triple bond is always given a lower locant than a double bond.

View answer and explanation

Correct option: D

If both the assertion and reason are false

Option A (Li) is correct because after the removal of one electron, Lithium attains a noble gas configuration, requiring significantly higher energy for the second ionization.

152 Medium

152 of 195

Understanding +4 | -1

The pair of electrons in the given carbanion,

C{H_3}\,C \equiv {C^ - }

, is present in which of the following orbitals

View answer and explanation

Correct option: B

SP

Option B (

SP

) is correct because the carbanion is attached to a triply bonded carbon, which is sp hybridized, and the lone pair resides in the sp hybrid orbital.

153 Medium

153 of 195

Understanding +4 | -1

Assertion (A): Kjeldahl's method is not applicable to compounds containing nitrogen in the form of nitro and azo groups and nitrogen present in the ring (e.g. pyridine).

Reason (R): Nitrogen of nitro and azo group containing compounds does not change to ammonium sulphate by Kjeldahl's method.

View answer and explanation

Correct option: A

Both

\mathrm{A}

and

\mathrm{R}

are correct ;

\mathrm{R}

is the correct explanation of

A

Option A is correct because Kjeldahl's method is unsuitable for compounds with nitrogen in nitro, azo groups, or rings, as their nitrogen doesn't convert to ammonium sulfate.

154 Medium

154 of 195

Application +4 | -1

The conversion of propan-1-ol to n-butylamine involves the sequential addition of reagents. The correct sequential order of reagents is

View answer and explanation

Correct option: A

({\text{i}})\,\,SOC{l_2}\,\,({\text{ii}})\,\,KCN\,\,({\text{iii}}){H_2}/Ni,Na(Hg)/{C_2}{H_5}OH

Option A is correct because it outlines the sequential reactions to convert propan-1-ol to n-butylamine via chlorination, cyanation, and reduction.

155 Medium

155 of 195

Understanding +4 | -1

Flourine cannot be tested by sodium fusion Lassaigne's test because

View answer and explanation

Correct option: B

AgF

is soluble in water

Option B (

AgF

is soluble in water) is correct because the solubility of

AgF

in water prevents the formation of a precipitate, which is necessary for detection in the Lassaigne's test.

156 Medium

156 of 195

Analyzing +4 | -1

How many isomeric vicinal-dihalides are possible for the compound having molecular formula

{C_3}{H_6}C{l_2}?

View answer and explanation

Correct option: D

Option D is correct because only one structure is possible for vicinal dihalides of the given compound.

157 Medium

157 of 195

Understanding +4 | -1

Which of the following is a false statement?

View answer and explanation

Correct option: B

Carius method is used for the estimation of nitrogen in an organic compound

Option B (Carius method is used for the estimation of nitrogen in an organic compound) is correct because Carius method is used for sulfur estimation, while Kjeldahl's and Duma's methods are used for nitrogen.

158 Medium

158 of 195

Understanding +4 | -1

A molecule having three different chiral carbon atoms, how many stereoisomers it will have?

View answer and explanation

Correct option: A

Option A is correct because the number of stereoisomers is calculated using the formula

2^n

, where n is the number of chiral carbon atoms. In this case,

2^3 = 8

159 Medium

159 of 195

Remembering +4 | -1

Which colour precipitate is obtained by reaction of phosphate radical with ammonium molybdate

View answer and explanation

Correct option: C

Canary yellow

Option C (Canary yellow) is correct because phosphate ions react with ammonium molybdate in the presence of nitric acid to form a canary yellow precipitate of ammonium phosphomolybdate.

160 Medium

160 of 195

Understanding +4 | -1

Which of the following is not an electrophile?

View answer and explanation

Correct option: D

{NH}_3

Option D (

{NH}_3

) is correct because it is a Lewis base and donates electrons, while electrophiles accept electrons.

161 Medium

161 of 195

Understanding +4 | -1

Assertion (A): A species having a carbon atom possessing sextext of electrons and a positive charge is called a carbocation.
Reason (R): A species having a carbon carrying a negative charge on carbon atom is called carbanion.

View answer and explanation

Correct option: B

Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

Option B (Both (A) & (R) are true but the (R) is not the correct explanation of the (A)) is correct because both the assertion and reason are correct statements, but the reason does not explain the assertion.

162 Medium

162 of 195

Understanding +4 | -1

A mixture of camphor and benzoic acid can be separated by

View answer and explanation

Correct option: A

Chemical method

Option C (Sublimation) is correct because camphor sublimes while benzoic acid does not, allowing for their separation by heating the mixture and collecting the sublimed camphor.

163 Medium

163 of 195

Understanding +4 | -1

Which of the following is not a meta-directing substituent when present on the benzene ring?

View answer and explanation

Correct option: A

-\mathrm{NHCOCH}_3

Option A (

-\mathrm{NHCOCH}_3

) is correct because it is an ortho-para directing group due to resonance (+R effect), while the others are meta-directing due to electron-withdrawing inductive or resonance effects.

164 Medium

164 of 195

Understanding +4 | -1

The IUPAC name of ethylidene chloride is:

View answer and explanation

Correct option: D

1, 1-Dichloroethane

Option D (1, 1-Dichloroethane) is correct because ethylidene chloride has the structure CH3-CHCl2, which corresponds to 1,1-dichloroethane in IUPAC nomenclature.

165 Medium

165 of 195

Analyzing +4 | -1

Consider the following nucleophilic groups :

\text{I. } -\mathrm{O}-\mathrm{SO}_2-\mathrm{C}_6 \mathrm{H}_5

{\text{II}}.\,\, - {\text{O}} - \mathop {\text{C}}\limits^{\begin{array}{cccccccccccccccccccc} {\text{O}} \\ {||} \end{array}} - {\text{C}}{{\text{H}}_3}

\text{III. }-{Cl}

\text{IV. }-\mathrm{OCH}_3

What is the correct order of leaving power of the above nucleophilic substitution reaction?

View answer and explanation

Correct option: C

\text{IV}>\text{III}>\text{II}>\text{I}

Option D (

\text{I}>\text{II}>\text{III}>\text{IV}

) is correct because the leaving group ability is related to the stability of the leaving group after it departs, with stronger acids being better leaving groups.

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166 Medium

166 of 195

Analyzing +4 | -1

The number of enantiomers of the compound

C{H_3}CH(Br)CH\left( {Br} \right)COOH

is:

View answer and explanation

Correct option: C

The correct answer is 4 because the compound has two chiral centers, and since there is no plane of symmetry, the number of stereoisomers (enantiomers) is 2^n = 2² = 4.

167 Medium

167 of 195

Understanding +4 | -1

Correct order of nucleophilicity is

View answer and explanation

Correct option: D

\mathrm{F}^{-} < \mathrm{OH}^{-} < \mathrm{NH}_2^{-} < \mathrm{CH}_3^{-}

Option D (

\mathrm{F}^{-} < \mathrm{OH}^{-} < \mathrm{NH}_2^{-} < \mathrm{CH}_3^{-}

) is correct because nucleophilicity increases as electronegativity decreases.

168 Medium

168 of 195

Remembering +4 | -1

The weakest +M group of the given species is:

View answer and explanation

Correct option: C

-\text{I}

Option C (-I) is correct because iodine has the least electron-donating ability among the given options due to its larger size and lower electronegativity.

169 Medium

169 of 195

Application +4 | -1

How many optically active forms are possible for a compound of the formula,

\mathrm{CHO}.\mathrm{CHOH}.\mathrm{CHOH}.\mathrm{CHOH}.\mathrm{C}{\mathrm{H}_2}\mathrm{OH}

View answer and explanation

Correct option: D

Option D (8) is correct because the number of optically active forms is calculated using the formula 2^n, where n is the number of chiral centers.

170 Medium

170 of 195

Understanding +4 | -1

But-2-ene exhibits cis-trans-isomerism due to

View answer and explanation

Correct option: B

restricted rotation around

\mathrm{C}=\mathrm{C}

bond

Option B is correct because cis-trans isomerism (geometric isomerism) in alkenes arises due to the restricted rotation around the carbon-carbon double bond.

171 Medium

171 of 195

Remembering +4 | -1

Lassaigne’s test is used for detection of

View answer and explanation

Correct option: B

Nitrogen, Sulphur, Phosphorous and halogens

Option B (Nitrogen, Sulphur, Phosphorous and halogens) is correct because Lassaigne's test is used to detect these elements in organic compounds.

172 Medium

172 of 195

Analyzing +4 | -1

Among the following the dissociation constant is highest for

View answer and explanation

Correct option: C

\mathrm{C}{\mathrm{H}_3} - \mathrm{C} \equiv \mathrm{CH}

Option C (

\mathrm{C}{\mathrm{H}_3} - \mathrm{C} \equiv \mathrm{CH}

) is correct because it has the highest dissociation constant due to the acidic nature of the proton attached to the sp-hybridized carbon.

173 Medium

173 of 195

Understanding +4 | -1

Total number of positional isomers for

\mathrm{C}_5 \mathrm{H}_{12}

View answer and explanation

Correct option: A

Zero

Option A (Zero) is correct because positional isomers require a minimum of 6 carbon atoms in an alkane.

174 Medium

174 of 195

Analyzing +4 | -1

Statement I: trans-2-Butane on reaction with

{Br}_2

gives meso-2,3-dibromobutane.

Statement II: The reaction involves syn-addition of bromine.

View answer and explanation

Correct option: C

Statement I is correct but statement II is incorrect

Option C is correct because trans-2-butene reacts with Br2 to give meso-2,3-dibromobutane, which involves anti-addition, not syn-addition.

175 Medium

175 of 195

Analyzing +4 | -1

What is the correct order of decreasing stability of the following cations

I)

C{H_3} - \mathop C\limits^ \oplus H - C{H_3}

II)

C{H_3} - \mathop C\limits^ \oplus H - OC{H_3}

III)

C{H_3} - \mathop C\limits^ \oplus H - OC{H_3}

View answer and explanation

Correct option: A

II > I > III

The correct answer is B (II > III > I) because the carbocation is stabilized by the +R effect of the methoxy group in II and III, with II being more stable due to less steric hindrance.

176 Medium

176 of 195

Analyzing +4 | -1

The number of isomers in

{\mathrm{C}_4}{\mathrm{H}_{10}}\mathrm{O}

are

View answer and explanation

Correct option: A

Option A (7) is correct because there are 7 structural isomers of

{\mathrm{C}_4}{\mathrm{H}_{10}}\mathrm{O}

, including 4 alcohols and 3 ethers.

177 Medium

177 of 195

Analyzing +4 | -1

Which is the correct order of stability of the following three carbonium ions?

\mathop {{\text{C}}{{\text{H}}_2} = {\text{CH}}\mathop {\text{C}}\limits^ + {{\text{H}}_3}}\limits_{\text{I}} ,\,\,\mathop {{\text{CH}} = \mathop {\text{C}}\limits^{\begin{array}{cccccccccccccccccccc} {{\text{C}}{{\text{H}}_3}} \\ {||} \end{array}} - {\text{C}}{{\text{H}}_2}}\limits_{{\text{II}}} ,\,\,\mathop {{\text{C}}{{\text{H}}_3}{\text{CH}} = {\text{CH}}\mathop {\text{C}}\limits^ + {{\text{H}}_2}}\limits_{{\text{III}}}

View answer and explanation

Correct option: C

\approx

III

>

Option C is correct. Carbocations are stabilized by +I effect and delocalization. I and III are more stable than II due to more delocalization.

178 Medium

178 of 195

Understanding +4 | -1

Aryl halides are less reactive towards nucleophilic substitution reaction as compared to alkyl due halides to:

View answer and explanation

Correct option: B

Resonance stabilization

Option B (Resonance stabilization) is correct because the aryl halides are less reactive towards nucleophilic substitution reactions due to the resonance stabilization of the C-X bond, which makes it stronger and harder to break.

179 Medium

179 of 195

Analyzing +4 | -1

The sum of geometrical isomers in

\left[\mathrm{Pt}\left(\mathrm{H}_2 \mathrm{~N}-\mathrm{CH}\left(\mathrm{CH}_3\right) \mathrm{COO}^{-}\right)_2\right]

complex and stereoisomers of

\left[\mathrm{Pt}(\text { gly })_3\right]^{+}

complex is

View answer and explanation

Correct option: A

Option A (If both assertion and reason are true and reason is the correct explanation of assertion) is correct because alcoholic silver nitrite (

AgNO_2

) is covalent, leading to the formation of nitroethane instead of ethyl nitrite.

180 Medium

180 of 195

Analyzing +4 | -1

Assertion (A): Carboxylic acid is more acidic than carbolic acid.

Reason (R): Carboxylic acid have equivalent resonating structure.

View answer and explanation

Correct option: C

(A) is true but (R) is false

Option C is correct. Carboxylic acids are more acidic than phenols, but the reason given about equivalent resonating structures is false. The resonance structures in carboxylate ions are not equivalent.

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