Hydrocarbons - Organic Chemistry - Chemistry Previous Year Questions

1

2016 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2016

Identify X in the following sequence of reactions.

A

B

C

D

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2

2016 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2016

Which of the following reactions will not result in the formation of carbon-carbon bonds?

A

Cannizzaro reaction

B

Wurtz reaction

C

Reimer-Tiemann reaction

D

Friedel-Crafts acylation

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3

2016 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2016

Ozonolysis of an alkene produces only one dicarbonyl compound. The structure of the alkene is

A

H₃C \(-\) CH \(=\) CH \(-\) CH₃

B

C

D

CH₃ \(-\) CH \(=\) CH \(-\) CH \(=\) CH₂

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4

2016 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2016

The major products obtained during ozonolysis of 2, 3-dimethyl-1-butene and subsequent reductions with Zn and H₂O are

A

methanoic acid and 2-methyl-2-butanone

B

methanal and 3-methyl-2-butanone

C

methanol and 2, 2-dimethyl-3-butanone

D

methanoic acid and 2-methyl-3-butanone

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5

2017 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2017

The isomerisation of 1-butyne to 2-butyne can be achieved by treatment with

A

hydrochloric acid

B

ammoniacal silver nitrate

C

ammoniacal cuprous chloride

D

ethanolic potassium hydroxide

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6

2018 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2018

CH₃ \(-\) C \(\equiv\) C MgBr can be prepared by the reaction of

A

CH₃ \(-\) C \(\equiv\) C \(-\) Br with MgBr₂

B

CH₃ \(-\) C \(\equiv\) CH with MgBr₂

C

CH₃ \(-\) C \(\equiv\) CH with KBr and Mg metal

D

CH₃ \(-\) C \(\equiv\) CH with CH₃MgBr

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7

2020 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2020

The total number of alkyl bromides (including stereoisomers) formed in the reaction \(M{e_3}C - CH = C{H_2} + HBr \to\) will be

A

1

B

2

C

3

D

No bromide forms

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8

2020 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2020

$$Me - C \equiv C - Me\mathrel{\mathop{\kern0pt\longrightarrow} \[\limits_{EtOH, - 33^\circ C}^{Na/N{H_3}(liq.)}} \underline{\underline X} \,\buildrel {dil.alkaline\,KMn{O_4}} \over\] \longrightarrow \,\text{Product(s)}$$

The product(s) from the above reaction will be

A

B

C

D

Check answer

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9

2020 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2020

Which of the following reactions give(s) a meso-compound as the main product?

A

B

C

D

Check answer

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10

2021 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2021

The exact order of boiling points of the compounds n-pentane, isopentane, butanone and 1-butanol is

A

n-pentane < isopentane < butanone < 1-butanol

B

isopentane < n-pentane < butanone < 1-butanol

C

butanone < n-pentane < isopentane < 1-butanol

D

1-butanol < butanone < n-pentane < isopentane

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11

2022 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2022

The major product of the following reaction is

$${F_3}C - CH = C{H_2} + HBr \to$$

A

\({F_3}C - C{H_2} - C{H_2}Br\)

B

\({F_3}C - CH(Br) - C{H_3}\)

C

D

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12

2023 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2023

Structure of M is,

A

\(\mathrm{Ph-C\equiv CH}\)

B

\(\mathrm{Ph-C\equiv C-CH_3}\)

C

\(\mathrm{H_3C-C\equiv CH}\)

D

\(\mathrm{H_3C-C\equiv C-CH_3}\)

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13

2023 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2023

'\(\underline G\)' in the above sequence of reactions is

A

\({(C{H_3})_2}CHCOOC{H_2}C{H_3}\)

B

\(C{H_3}C{H_2}C{H_2}COOC{H_2}C{H_3}\)

C

\(C{H_3}C{H_2}COOC{H_2}C{H_2}C{H_3}\)

D

\(C{H_3}C{H_2}COOCH{(C{H_3})_2}\)

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14

2024 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2024

The compounds A and B are respectively

A

B

C

D

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15

2024 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2024

The decreasing order of reactivity of the following alkenes towards \(\mathrm{HBr}\) addition is

A

I > II > III > IV

B

II > IV > I > III

C

III > IV > I > II

D

III > I > II > IV

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16

2024 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2024

Which of the following statements about the \(\mathrm{S}_{\mathrm{N}} 2\) reaction mechanism is/are true?

A

The rate of reaction increases with increasing nucleophilicity.

B

The number 2 denotes a second order reaction.

C

Tertiary butyl substrates do not follow this mechanism.

D

The optical rotation of substrates always changes from (+) to \((-)\) or from \((-)\) to (+) in the products.

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17

2024 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2024

\(\mathrm{Q}\) and \(\mathrm{R}\) in the above reaction sequences are respectively

A

\(\mathrm{Hg}(\mathrm{OAc})_2, \mathrm{NaBH}_4 / \overline{\mathrm{O}} \mathrm{H} ; \mathrm{B}_2 \mathrm{H}_6, \mathrm{H}_2 \mathrm{O}_2 / \overline{\mathrm{O}} \mathrm{H}\)

B

\(\mathrm{B}_2 \mathrm{H}_6, \mathrm{H}_2 \mathrm{O}_2 / \overline{\mathrm{O}} \mathrm{H} ; \mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}\)

C

\(\mathrm{Hg}(\mathrm{OAc})_2, \mathrm{NaBH}_4/ \overline{\mathrm{O}} \mathrm{H} ; \mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}\)

D

\(\mathrm{B}_2 \mathrm{H}_6, \mathrm{H}_2 \mathrm{O}_2 / \overline{\mathrm{O}}\mathrm{H} ; \mathrm{Hg}(\mathrm{OAc})_2, \mathrm{NaBH}_4 / \overline{\mathrm{O}} \mathrm{H}\)

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18

2025 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2025

An optically active alkene having molecular formula $\mathrm{C}_8 \mathrm{H}_{16}$ gives acetone as one of the products on ozonolysis. The structure of the alkene is

A

B

C

D

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19

2025 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2025

Which of the following hydrocarbons reacts easily with $\mathrm{MeMgBr}$ to give methane?

A

B

C

D

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20

2026 · Chemistry · Organic Chemistry · Hydrocarbons

WB JEE 2026

In the following reaction sequence, the product Y is

$$\mathrm{Br}\left(\mathrm{CH}_2\right)_{12}-\mathrm{C} \equiv \mathrm{CH} \xrightarrow{\mathrm{NaNH}_2} \mathrm{X} \xrightarrow[\text { catalyst }]{\mathrm{H}_2, \text { Lindler }} \mathrm{Y}$$

A

B

C

\(\mathrm{Br}\left(\mathrm{CH}_2\right)_{12}-\mathrm{CH}=\mathrm{CH}_2\)

D

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