PYQSide ExamsMy practice

Isomerism · Question 20

NEET 2013 (Karnataka)MCQMedium📈 Topic in 0% papers+4−1
1

Given: [figure] I and II are

  1. identical
  2. a pair of conformers
  3. a pair of geometrical isomers
  4. a pair of optical isomers

Answer

(2) a pair of conformers

Solution

Both I and II are sawhorse projections of 2,3-dibromobutane, CH3-CHBr-CHBr-CH3.

Front carbon: going clockwise, the order CH3 H Br is the same in I and II.

Rear carbon: going clockwise, the order Br CH3 H is the same in I and II.

∴ Both carbons have the same configuration in I and II; the two drawings differ only in the relative position of the groups on the front and rear carbons.

⇒ II is obtained from I by rotation about the C2–C3 single bond.

∴ As per NCERT, such spatial arrangements obtained by rotation about a C–C single bond are conformations ⇒ I and II are a pair of conformers.

Answer: (2)

NEET 2013 (Karnataka)

Keep practising — Isomerism

2

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

  1. three
  2. four
  3. five
  4. two
NEET 2013 (Karnataka)
3

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)
4

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)
5

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

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

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2010 (Prelims)
7

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

  1. Butanol
  2. 2-Butyne
  3. 2-Butanol
  4. 2-Butene
AIPMT 2009
8

How many stereoisomers does this molecule have? CH3CH=CHCH2CHBrCH3

  1. 8
  2. 2
  3. 4
  4. 6
AIPMT 2008
9

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
10

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
11

Which of the following is not chiral?

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

All Isomerism PYQs →

PDFDownload Isomerism PYQs as PDF Free, with answer key and a QR code to every solution — print it or study offline⬇
All NEET Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolid StateSolutionsElectrochemistryChemical KineticsSurface Chemistry
Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular StructureHydrogens-Block Elementsp-Block Elements (Group 13 & 14)Environmental ChemistryGeneral Principles of Isolation of Elementsp-Block Elements (Group 15–18)d- and f-Block ElementsCoordination Compounds
Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPolymersChemistry in Everyday LifePrinciples Related to Practical Chemistry