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Hydrocarbons · Question 6

NEET (UG) 2025MCQEasy📈 Topic in 62% papers+4−1
1

Which one of the following compounds does not decolourize bromine water?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(3) [figure]

Solution

As per NCERT, decolourisation of bromine water is a test for unsaturation; activated arenes (phenol, aniline) also decolourise it by electrophilic substitution.

(1) Styrene: Br2 adds across the C=C bond of the side chain, so the colour disappears.

(2) Aniline: the strongly activating -NH2 group gives 2,4,6-tribromoaniline (white precipitate).

(3) Cyclohexane: a saturated hydrocarbon; it neither adds nor substitutes bromine under these conditions, so the colour stays.

(4) Phenol: gives 2,4,6-tribromophenol (white precipitate).

Answer: (3)

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2

Given below are two statements: In the light of the above statements, choose the most appropriate answer from the options given below:

  1. Both Statement I and Statement II are correct
  2. Both Statement I and Statement II are incorrect
  3. Statement I is correct but Statement II is incorrect
  4. Statement I is incorrect but Statement II is correct
NEET (UG) 2024
3

For the given reaction: [figure] 'P' is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
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4

Baeyer's reagent is :

  1. Acidic potassium permanganate solution
  2. Acidic potassium dichromate solution
  3. Cold, dilute, aqueous solution of potassium permanganate
  4. Hot, concentrated solution of potassium permanganate
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5

The alkane that can be oxidized to the corresponding alcohol by KMnO4 as per the equation [figure] is, when :

  1. R1 = H; R2 = H; R3 = H
  2. R1 = CH3; R2 = CH3; R3 = CH3
  3. R1 = CH3; R2 = H; R3 = H
  4. R1 = CH3; R2 = CH3; R3 = H
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6

Weight (g) of two moles of the organic compound, which is obtained by heating sodium ethanoate with sodium hydroxide in presence of calcium oxide is :

  1. 32
  2. 30
  3. 18
  4. 16
Out of syllabusNEET (UG) 2023
7

Compound X on reaction with O3 followed by Zn/H2O gives formaldehyde and 2-methyl propanal as products. The compound X is

  1. 3-Methylbut-1-ene
  2. 2-Methylbut-1-ene
  3. 2-Methylbut-2-ene
  4. Pent-2-ene
NEET (UG) 2022
8

The decreasing order of boiling points of the following alkanes is : Choose the correct answer from the options given below :

  1. A > E > C > B > D
  2. A > C > E > D > B
  3. C > D > A > E > B
  4. A > E > B > C > D
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9

The incorrect method for the synthesis of alkenes is

  1. Treating vicinal dihalides with Zn metal
  2. Treating of alkynes with Na in liquid NH3
  3. Heating alkyl halides with alcoholic KOH
  4. Treating alkyl halides in aqueous KOH solution
NEET (UG) 2022 (Phase 2)
10

The major product of the following chemical reaction is : [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET (UG) 2021
11

CH3CH2COO-Na+ [Heat]NaOH, +? CH3CH3 + Na2CO3 Consider the above reaction and identify the missing reagent/chemical.

  1. DIBAL-H
  2. B2H6
  3. Red Phosphorus
  4. CaO
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