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Organic Chemistry – Some Basic Principles and Techniques · Question 23

NEET 2017MCQMedium📈 Topic in 0% papers+4−1
1

Which one is the correct order of acidity?

  1. CH CH > CH3-C CH > CH2=CH2 > CH3-CH3
  2. CH CH > CH2=CH2 > CH3-C CH > CH3-CH3
  3. CH3-CH3 > CH2=CH2 > CH3-C CH > CH CH
  4. CH2=CH2 > CH3-CH=CH2 > CH3-C CH > CH CH

Answer

(1) CH CH > CH3-C CH > CH2=CH2 > CH3-CH3

Solution

Acidic strength of C–H ∝ % s-character of carbon: sp (50%) > sp2 (33%) > sp3 (25%).

⇒ Alkynes > alkenes > alkanes

Among alkynes, CH CH has two acidic H and no electron-releasing group; in CH3-C CH the -CH3 group (+I effect) decreases acidity.

∴ CH CH > CH3-C CH > CH2=CH2 > CH3-CH3

Answer: (1)

NEET 2017

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2

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.
NEET 2016 (Phase 1)
3

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)
4

In which of the following molecules, atoms are coplanar?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET 2016 (Phase 2)
5

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)
6

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
7

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

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

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)
9

Consider the following compounds : [figure] Hyperconjugation occurs in

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

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)
11

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)

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