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Organic Chemistry – Some Basic Principles and Techniques · Question 40

NEET 2013 (Karnataka)MCQMedium📈 Topic in 38% papers+4−1
1

Arrange the following in increasing order of stability 1. (CH3)2- C-CH2-CH3 2. (CH3)3- C 3. (CH3)2- CH 4. CH3- CH2 5. CH3

  1. 5 < 4 < 3 < 1 < 2
  2. 4 < 5 < 3 < 1 < 2
  3. 1 < 5 < 4 < 3 < 2
  4. 5 < 4 < 3 < 2 < 1

Answer

(1) 5 < 4 < 3 < 1 < 2

Solution

Stability of carbocations: 3° > 2° > 1° > methyl, due to +I effect and hyperconjugation of alkyl groups.

5 ( CH3, methyl) < 4 (1°) < 3 (2°, isopropyl) < tertiary cations 1 and 2

Between the two 3° cations:

2 (tert-butyl) has 9 α-hydrogens; 1 (tert-pentyl) has 8 α-hydrogens.

⇒ 2 has more hyperconjugative structures, so 1 < 2.

∴ 5 < 4 < 3 < 1 < 2

Answer: (1)

NEET 2013 (Karnataka)

Keep practising — Organic Chemistry – Some Basic Principles and Techniques

2

What is the hybridisation state of benzyl carbonium ion? [figure]

  1. sp2
  2. spd2
  3. sp2d
  4. sp3
NEET 2013 (Karnataka)
3

Homolytic fission of the following alkanes forms free radicals CH3-CH3, CH3-CH2-CH3, (CH3)2CH-CH3, CH3-CH2-CH(CH3)2. Increasing order of stability of the radicals is

  1. (CH3)2 C-CH2CH3 < CH3- CH-CH3 < CH3- CH2 < (CH3)3 C
  2. CH3- CH2 < CH3- CH-CH3 < (CH3)2 C-CH2-CH3 < (CH3)3 C
  3. CH3- CH2 < CH3- CH-CH3 < (CH3)3 C < (CH3)2 C-CH2CH3
  4. (CH3)3 C < (CH3)2 C-CH2CH3 < CH3- CH-CH3 < CH3- CH2
NEET 2013 (Karnataka)
4

Which of the following chemical system is non aromatic?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET 2013 (Karnataka)
5

Which nomenclature is not according to IUPAC system?

  1. Br-CH2-CH=CH2 1-Bromoprop-2-ene
  2. [figure] 4-Bromo-2,4-dimethylhexane
  3. [figure] 2-Methyl-3-phenylpentane
  4. [figure] 5-Oxohexanoic acid
AIPMT 2012 (Prelims)
6

Which one of the following is most reactive towards electrophilic reagent?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2011 (Prelims)
7

The correct IUPAC name for the compound is [figure]

  1. 4-ethyl-3-propylhex-1-ene
  2. 3-ethyl-4-ethenylheptane
  3. 3-ethyl-4-propylhex-5-ene
  4. 3-(1-ethylpropyl)hex-1-ene
AIPMT 2011 (Prelims)
8

Which of the following species is not electrophilic in nature?

  1. Cl
  2. BH3
  3. H3 O
  4. NO2
AIPMT 2010 (Mains)
9

The IUPAC name of the compound CH3CH=CHC CH is

  1. pent-4-yn-2-ene
  2. pent-3-en-1-yne
  3. pent-2-en-4-yne
  4. pent-1-yn-3-ene
AIPMT 2010 (Mains)
10

Which one of the following is most reactive towards electrophilic reagent?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2010 (Prelims)
11

The IUPAC name of the compound having the formula CH C-CH=CH2 is

  1. 1-butyne-3-ene
  2. but-1-yne-3-ene
  3. but-1-en-3-yne
  4. 3-butene-1-yne.
AIPMT 2009

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