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NEET UG Organic Chemistry: Some Basic Principles and Techniques — practice questions — page 3

Explore 101 free Organic Chemistry: Some Basic Principles and Techniques questions in NEET UG Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Organic Chemistry: Some Basic Principles and Techniques questions and exercises with answers

Showing questions 61–90 of 101.

As an acid becomes stronger, its pKa valueRead the answer and worked solution →Benzoic acid is stronger than cyclohexanecarboxylic acid because its ring carbons areRead the answer and worked solution →Diacids are usually stronger because a carboxyl group isRead the answer and worked solution →A positively charged carbon attached to a +I group becomesRead the answer and worked solution →Attaching more +I groups to a molecule generallyRead the answer and worked solution →When the attacking reagent is an electrophile, which electromeric effect is generally seen?Read the answer and worked solution →The concepts of electromeric and mesomeric effects are now absorbed into which broader term?Read the answer and worked solution →A carbocation is an ion containingRead the answer and worked solution →What is the usual hybridisation of the positive carbon in a simple carbenium ion?Read the answer and worked solution →The LUMO on the charged carbon of a planar carbenium ion isRead the answer and worked solution →How many valence electrons surround the positive carbon of a carbenium ion?Read the answer and worked solution →What is the coordination number of the charged carbon in a carbonium ion such as CH5+?Read the answer and worked solution →Extra methyl groups stabilise a carbocation by hyperconjugation as they add moreRead the answer and worked solution →Hyperconjugation is also known asRead the answer and worked solution →Hyperconjugation involves delocalisation of electrons fromRead the answer and worked solution →By hyperconjugation, alkenes become more stable whenRead the answer and worked solution →Hyperconjugation is proposed to explain why ethane prefers itsRead the answer and worked solution →A nucleophile forms bonds byRead the answer and worked solution →Because they donate electron pairs, nucleophiles are classed asRead the answer and worked solution →Between comparable sulfur and oxygen nucleophiles, which is generally stronger?Read the answer and worked solution →An ion such as thiocyanate, which can attack through two different atoms, is calledRead the answer and worked solution →Grignard reagents and organolithium compounds commonly serve asRead the answer and worked solution →A nucleophilic reaction in which a neutral solvent such as water or an alcohol is the nucleophile is calledRead the answer and worked solution →Which of these species behaves as an electrophile?Read the answer and worked solution →Carbenes and free radicals can act as electrophiles mainly because theyRead the answer and worked solution →Resonance in molecules is also calledRead the answer and worked solution →Compared with any single contributor, the resonance hybrid isRead the answer and worked solution →Resonance energy is the energy gap between the real molecule andRead the answer and worked solution →All resonance contributors of a species must have the sameRead the answer and worked solution →Resonance contributors of a molecule differ from one another only in theRead the answer and worked solution →

Worked practice questions

As an acid becomes stronger, its pKa value

  1. Increases steadily
  2. Decreases numerically
  3. Always turns negative
  4. Remains unchanged
Show answer and solution

Correct answer: B. Decreases numerically

pKa is the negative logarithm of the ionisation constant, so greater ionisation gives a smaller pKa.

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Benzoic acid is stronger than cyclohexanecarboxylic acid because its ring carbons are

  1. sp hybridised
  2. dsp2 hybridised
  3. sp2 hybridised
  4. sp3 hybridised
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Correct answer: C. sp2 hybridised

The sp2 ring carbons of benzoic acid are more electronegative than sp3 carbons, so they help stabilise the carboxylate.

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Diacids are usually stronger because a carboxyl group is

  1. A strongly basic group
  2. A neutral non-polar group
  3. An electron-withdrawing group
  4. An electron-donating group
Show answer and solution

Correct answer: C. An electron-withdrawing group

The second carboxyl group pulls electron density away and helps the first one ionise more easily.

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More Chemistry topics

Amines and BiomoleculesChemical KineticsAldehydes, Ketones and Carboxylic AcidsEquilibriumRedox ReactionsHydrocarbonsChemical Bonding and Molecular StructureSolutions