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Organic Chemistry – Some Basic Principles and Techniques · Question 26

NEET 2016 (Phase 2)MCQMedium📈 Topic in 0% papers+4−1
1

In which of the following molecules, atoms are coplanar?

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

Answer

(1) [figure]

Solution

(1) Biphenyl: all 12 C atoms are sp2 and the two rings are joined by a C–C single bond; the molecule is planar (as in the solid), so all its atoms lie in one plane.

(2) Cyclohexane: sp3 carbons ⇒ non-planar (chair form).

(3) The two CH3 carbons are sp3 ⇒ their H atoms cannot all lie in the molecular plane.

(4) Bicyclohexyl: all carbons sp3 ⇒ non-planar.

Answer: (1)

NEET 2016 (Phase 2)

Keep practising — Organic Chemistry – Some Basic Principles and Techniques

2

In pyrrole the electron density is maximum on [figure]

  1. 2 and 3
  2. 3 and 4
  3. 2 and 4
  4. 2 and 5
NEET 2016 (Phase 2)
3

Which of the following statements is not correct for a nucleophile?

  1. Ammonia is a nucleophile.
  2. Nucleophiles attack low e- density sites.
  3. Nucleophiles are not electron seeking.
  4. Nucleophile is a Lewis acid.
AIPMT 2015
4

The total number of π-bond electrons in the following structure is [figure]

  1. 12
  2. 16
  3. 4
  4. 8
AIPMT 2015 (Cancelled)
5

Which of the following is the most correct electron displacement for a nucleophilic reaction to take place?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2015 (Cancelled)
6

Consider the following compounds : [figure] Hyperconjugation occurs in

  1. III only
  2. I and III
  3. I only
  4. II only
AIPMT 2015 (Cancelled)
7

The enolic form of ethyl acetoacetate as shown below has [figure]

  1. 9 sigma bonds and 2 pi-bonds
  2. 9 sigma bonds and 1 pi-bond
  3. 18 sigma bonds and 2 pi-bonds
  4. 16 sigma bonds and 1 pi-bond.
AIPMT 2015 (Cancelled)
8

In which of the following compounds, the C–Cl bond ionisation shall give most stable carbonium ion?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2015 (Cancelled)
9

Given : [figure] The enthalpy of hydrogenation of these compounds will be in the order as

  1. II > III > I
  2. II > I > III
  3. I > II > III
  4. III > II > I
AIPMT 2015 (Cancelled)
10

Which of the following organic compounds has same hybridization as its combustion product (CO2)?

  1. Ethane
  2. Ethyne
  3. Ethene
  4. Ethanol
AIPMT 2014
11

The radical, [figure] is aromatic because it has

  1. 7 p-orbitals and 7 unpaired electrons
  2. 6 p-orbitals and 7 unpaired electrons
  3. 6 p-orbitals and 6 unpaired electrons
  4. 7 p-orbitals and 6 unpaired electrons.
NEET 2013

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