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Isomerism · Question 21

NEET 2013 (Karnataka)MCQMedium📈 Topic in 25% papers+4−1
1

Number of isomeric alcohols of molecular formula C6H14O which give positive iodoform test is

  1. three
  2. four
  3. five
  4. two

Answer

(2) four

Solution

Iodoform test is given by alcohols having the CH3-CH(OH)-R unit.

For C6H14O ⇒ R = C4H9, which has four isomeric forms:

(i) CH3CH(OH)CH2CH2CH2CH3 (hexan-2-ol)

(ii) CH3CH(OH)CH2CH(CH3)2 (4-methylpentan-2-ol)

(iii) CH3CH(OH)CH(CH3)CH2CH3 (3-methylpentan-2-ol)

(iv) CH3CH(OH)C(CH3)3 (3,3-dimethylbutan-2-ol)

∴ Number of such alcohols = 4

Answer: (2)

NEET 2013 (Karnataka)

Keep practising — Isomerism

2

Which of the following acids does not exhibit optical isomerism?

  1. Maleic acid
  2. -amino acids
  3. Lactic acid
  4. Tartaric acid
AIPMT 2012 (Prelims)
3

The IUPAC name of the following compound is [figure]

  1. trans-2-chloro-3-iodo-2-pentene
  2. cis-3-iodo-4-chloro-3-pentene
  3. trans-3-iodo-4-chloro-3-pentene
  4. cis-2-chloro-3-iodo-2-pentene
AIPMT 2011 (Mains)
4

Which of the following conformers for ethylene glycol is most stable?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2010 (Mains)
5

In the following the most stable conformation of n-butane is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2010 (Prelims)
6

Which of the following compounds will exhibit cis-trans (geometrical) isomerism?

  1. Butanol
  2. 2-Butyne
  3. 2-Butanol
  4. 2-Butene
AIPMT 2009
7

How many stereoisomers does this molecule have? CH3CH=CHCH2CHBrCH3

  1. 8
  2. 2
  3. 4
  4. 6
AIPMT 2008
8

CH3-CHCl-CH2-CH3 has a chiral centre. Which one of the following represents its R-configuration?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2007
9

If there is no rotation of plane polarised light by a compound in a specific solvent, though thought to be chiral, it may mean that

  1. the compound is certainly meso
  2. there is no compound in the solvent
  3. the compound may be a racemic mixture
  4. the compound is certainly achiral.
AIPMT 2007
10

Which of the following is not chiral?

  1. 2-Hydroxypropanoic acid
  2. 2-Butanol
  3. 2,3-Dibromopentane
  4. 3-Bromopentane
AIPMT 2006
11

The chirality of the compound [figure]

  1. R
  2. S
  3. E
  4. Z
AIPMT 2005

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