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Organic Chemistry – Some Basic Principles and Techniques · Question 24

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

For the following reactions : (A) CH3CH2CH2Br + KOH CH3CH=CH2 + KBr + H2O (B) [figure] (C) [figure] Which of the following statements is correct?

  1. (A) is elimination, (B) and (C) are substitution reactions.
  2. (A) is substitution, (B) and (C) are addition reactions.
  3. (A) and (B) are elimination reactions and (C) is addition reaction.
  4. (A) is elimination, (B) is substitution and (C) is addition reaction.

Answer

(4) (A) is elimination, (B) is substitution and (C) is addition reaction.

Solution

(A) H and Br are removed from adjacent carbons to form a C=C bond ⇒ elimination (dehydrohalogenation).

(B) -Br of 2-bromopropane is replaced by -OH to give propan-2-ol ⇒ substitution.

(C) Br2 adds across the C=C bond of cyclohexene to give 1,2-dibromocyclohexane ⇒ addition.

∴ (A) is elimination, (B) is substitution and (C) is addition reaction.

Answer: (4)

NEET 2016 (Phase 1)

Keep practising — Organic Chemistry – Some Basic Principles and Techniques

2

The pair of electrons in the given carbanion, CH3C C-, is present in which of the following orbitals?

  1. sp2
  2. sp
  3. 2p
  4. sp3
NEET 2016 (Phase 1)
3

In which of the following molecules, atoms are coplanar?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET 2016 (Phase 2)
4

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)
5

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
6

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

  1. 12
  2. 16
  3. 4
  4. 8
AIPMT 2015 (Cancelled)
7

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)
8

Consider the following compounds : [figure] Hyperconjugation occurs in

  1. III only
  2. I and III
  3. I only
  4. II only
AIPMT 2015 (Cancelled)
9

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)
10

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)
11

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)

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