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Hydrocarbons

NEET (UG) 2021MCQEasy📈 Topic in 62% papers+4−1
Ques. 1NEET (UG) 2021

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

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

Answer

(1) [figure]

Solution

As per NCERT, in the presence of a peroxide such as benzoyl peroxide, HBr adds to an unsymmetrical alkene contrary to Markovnikov's rule (peroxide effect / Kharash effect), by a free-radical mechanism.

The peroxide gives phenyl radicals, (C6H5CO)2O2 2C6H5 CO2 2 C6H5 + 2CO2, which take H from HBr: C6H5 + HBr C6H6 + Br.

Br then adds to the terminal CH2 so that the more stable 2° radical, (CH3)2CH- CH-CH2Br, is formed, and this radical takes H from HBr:

(CH3)2CH- CH-CH2Br + HBr (CH3)2CH-CH2-CH2Br + Br

∴ Major product: 1-bromo-3-methylbutane, (CH3)2CH-CH2-CH2-Br

Answer: (1)

Keep practising — Hydrocarbons

Ques. 2NEET (UG) 2021

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
Ques. 3NEET (UG) 2020

Which of the following alkane cannot be made in good yield by Wurtz reaction?

  1. 2, 3-Dimethylbutane
  2. n-Heptane
  3. n-Butane
  4. n-Hexane
Ques. 4NEET (UG) 2020

An alkene on ozonolysis gives methanal as one of the products, Its structure is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 5NEET (UG) 2019

Among the following, the reaction that proceeds through an electrophilic substitution, is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 6NEET (UG) 2019

The most suitable reagent for the following conversion, is : [figure]

  1. Zn / HCl
  2. Hg2+/H+, H2O
  3. Na / liquid NH3
  4. H2, Pd/C, quinoline
Ques. 7NEET (UG) 2019

An alkene “A” on reaction with O3 and Zn + H2O gives propanone and ethanal in equimolar ratio. Addition of HCl to alkene “A” gives “B” as the major product. The structure of product “B” is :

  1. H3C-CH2- Cl | CH3 |C-CH3
  2. H3C- Cl |CH- CH3 | CH3 |CH
  3. Cl-CH2-CH2- CH3 | CH3 |CH
  4. H3C-CH2- CH2Cl |CH-CH3
Ques. 8NEET 2018

Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is

  1. CH CH
  2. CH2 = CH2
  3. CH3 - CH3
  4. CH4
Ques. 9NEET 2017

Predict the correct intermediate and product in the following reaction : H3C-C CH [HgSO4]H2O, H2SO4 (A)Intermediate (B)Product

  1. A : H3C- OH |C=CH2 B : H3C- SO4 |C=CH2
  2. A : H3C- O \|C-CH3 B : H3C-C CH
  3. A : H3C- OH |C=CH2 B : H3C- O \|C-CH3
  4. A : H3C- SO4 |C=CH2 B : H3C- O \|C-CH3
Ques. 10NEET 2016 (Phase 1)

Consider the nitration of benzene using mixed conc. H2SO4 and HNO3. If a large amount of KHSO4 is added to the mixture, the rate of nitration will be

  1. unchanged
  2. doubled
  3. faster
  4. slower
Ques. 11NEET 2016 (Phase 1)

In the reaction H-C CH [(ii) CH3CH2Br](i) NaNH2/liq. NH3 X [(ii) CH3CH2Br](i) NaNH2/liq. NH3 Y, X and Y are

  1. X = 2-Butyne, Y = 2-Hexyne
  2. X = 1-Butyne, Y = 2-Hexyne
  3. X = 1-Butyne, Y = 3-Hexyne
  4. X = 2-Butyne, Y = 3-Hexyne

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