Basics of Organic Chemistry (GOC)

NEET Chemistry · 63 questions · Page 3 of 7 · Click an option or "Show Solution" to reveal answer

Q21

Paper chromatography is an example of :

A Partition chromatography

B Thin layer chromatography

C Column chromatography

D Adsorption chromatography

Correct Answer

Option A

Solution

Paper chromatography is a type of partition chromatography in which a special quality paper known as chromatography paper is used.

Q22

A tertiary butyl carbocation is more stable than a secondary butyl carbocation because of which of the following?

A +R effect of

-

CH 3 groups

-

R effect of

-

CH 3 groups

C Hyperconjugation

-

I effect of

-

CH 3 groups

Correct Answer

Option C

Solution

More the number of $\alpha$ $-$ H atoms, more will be the hyper conjugation effect hence more will be the stability of carbocation.

Q23

The correct statement regarding electrophile is

A electrophile is a negatively charged species and form a bond by accepting a pair of electrons from another electrophile

B electrophiles are generally neutral species and can form a bond by accepting a pair of electrons from a nucleophile

C electrophile can be either neutral or positively charged species and can form a bond by accepting a pair of electrons from a nucleophile

D electrophile is a negatively charged species and can form a bond by accepting a pair of electrons from a nucleophile.

Correct Answer

Option C

Solution

Electrophile can be either neutral or positively charged species and can form a bond by accepting a pair of electrons from a nucleophile.

Q24

The most suitable method of separation of 1 : 1 mixture of ortho and para-nitrophenols is

A chromatography

B crystallisation

C steam distillation

D sublimation.

Correct Answer

Option C

Solution

Steam distillation is the most suitable method of separation of 1 : 1 mixture of ortho and para nitrophenols as there is intramolecular hydrogen bonding in o-nitrophenol.

Q25

Which among the given molecules can exhibit tautomerism?

A III only

B Both I and III

C Both I and II

D Both II and III

Correct Answer

Option A

Solution

$\alpha$ -hydrogen at bridge carbon never participates in tautomerism. Thus, only (III) exhibits tautomerism.

Q26

The correct statement regarding the comparison of staggered and eclipsed conformations of ethane, is

A the eclipsed conformation of ethane is more stable than staggered conformation even through the eclipsed conformation has torsional strain

B the staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain

C the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain

D the eclipsed conformation of ethane is more stable than stggered conformation, because eclipsed conformation has no torsional strain.

Correct Answer

Option B

Solution

In staggered conformation any two hydrogen atoms on adjacent carbon atoms are as far apart as possible there by minimising repulsion between the electron clouds $\sigma$ - of bonds of two non-bonded H-atomic (torsional strain)

Q27

The possible stereo-structures of CH 3 CHOHCOOH, which are optically active, are called

A atropisomers

B enantiomers

C mesomers

D diastereomers

Correct Answer

Option B

Solution

They are enantiomers (non-superimposable mirror images)

Q28

Which of the following statements is not correct for a nucleophile?

A Ammonia is a nucleophile.

B Nucleophiles attack low e

-

density sites.

C Nucleophiles are not electron seeking.

D Nucleophile is a Lewis acid.

Correct Answer

Option D

Solution

Nucleophile is a species that provide electron while species which are deficient of electrons are termed as lewis acid, hence nucleophiles are usually lewis bases.

Q29

Consider the following compounds : Hyperconjunction occurs in

A III only

B I and III

C I only

D II only

Correct Answer

Option A

Solution

Only structure (III) has $\alpha$ -H in conjugation with free radical. So, hyperconjugation is possible in III only.

Q30

The enolic form of ethyl accetoacetate as shown below has

A 9 sigma bonds and 2 pi-bonds

B 9 sigma bonds and 1 pi-bond

C 18 sigma bonds and 2 pi-bonds

D 16 sigma bonds and 1 pi-bond.

Correct Answer

Option C

Solution

The given structure has 18 $\sigma$ bonds and 2 $\pi$ bonds.

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