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Explore popular questions from Organic Chemistry Some Basic Principles and Techniques for NEET. This collection covers Organic Chemistry Some Basic Principles and Techniques previous year NEET questions hand picked by experienced teachers.

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Organic Chemistry Some Basic Principles and Techniques

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Q 1. The most suitable method of separation of {tex} 1 : 1 {/tex} mixture of {tex}ortho{/tex} and {tex}para{/tex}-nitrophenols is

A

chromatography

B

crystallisation

steam distillation

D

sublimation.

Explanation



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Q 2. The IUPAC name of the compound is

A

5-formylhex-2-en-3-one

B

5-methyl- 4 -oxohex- 2 -en- 5 - al

C

3-keto-2-methylhex-5-enal

3-keto-2-methylhex-4-enal

Explanation

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Q 3. The correct statement regarding electrophile is

A

electrophile is a negatively charged species and can 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

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.

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Q 4. Which among the given molecules can exhibit tautomerism?

III only

B

Both I and III

C

Both I and II

D

Both II and III

Explanation



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Q 5. Which of the following biphenyls is optically active?

A

B

C

Explanation


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Q 6. For the following reactions

Which of the following statements is correct?

A

(A) is elimination, (B) and (C) are substitution reactions.

B

(A) is substitution, (B) and (C) are addition reactions.

C

(A) and (B) are elimination reactions and (C) is addition reaction.

(A) is elimination, ( B) is substitution and (C) is addition reaction.

Explanation



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Q 7. Which of the following statements is not correct for a nucleophile?

A

Ammonia is a nucleophile.

B

Nucleophiles attack low {tex} e ^ { - } {/tex} density sites.

C

Nucleophiles are not electron seeking.

Nucleophile is a Lewis acid.

Explanation


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Q 8. Which of the following is not the product of dehydration of ?

B

C

D

Explanation



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Q 9. Treatment of cyclopentanone with methyl lithium gives which of the following species?

A

Cyclopentanonyl radical

B

Cyclopentanonyl biradical

Cyclopentanonyl anion

D

Cyclopentanonyl cation

Explanation

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Q 10. The total number of {tex} \pi {/tex} -bond electrons in the following structure is

A

12

B

16

C

4

8

Explanation


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Q 11. Given:

Which of the given compounds can exhibit tautomerism?

A

II and III

I, II and III

C

I and II

D

I and III

Explanation



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Q 12. Which of the following is the most correct electron displacement for a nucleophilic reaction to take place?

B

C

D

Explanation



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Q 13. In Duma's method for estimation of nitrogen, 0.25 g of an organic compound gave 40 mL of nitrogen collected at 300 K temperature and 725 mm presure. If the aqueous tension at 300 K is 25 mm, the percentage of nitrogen in the compound is

16.76

B

15.76

C

17.36

D

18.20

Explanation



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Q 14. Consider the following compounds

Hyperconjugation occurs in

III only

B

I and III

C

I only

D

II only.

Explanation


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Q 15. The enolic form of ethyl acetoacetate as shown below has

A

9 sigma bonds and 2 pi-bonds

B

9 sigma bonds and 1 pi-bond

18 sigma bonds and 2 pi-bonds

D

16 sigma bonds and 1 pi-bond.

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Q 16. In which of the following compounds, the C- Cl bond ionisation shall give most stable carbonium ion?

A

B

C

Explanation


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Q 17. In the Kjeldahl's method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75 g of sample neutralized 10{tex} \mathrm { mL } {/tex} of 1M {tex} \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } {/tex} . The percentage of nitrogen in the soil is

37.33

B

45.33

C

35.33

D

43.33

Explanation


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Q 18. The radical, is aromatic because it has

A

7{tex} p {/tex} -orbitals and 7 unpaired electrons

B

6{tex} p {/tex} -orbitals and 7 unpaired electrons

6{tex} p {/tex} -orbitals and 6 unpaired electrons

D

7{tex} p {/tex} -orbitals and 6 unpaired electrons.

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Q 19. The structure of isobutyl group in an organic compound is

A

B

D

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Q 20. Some {tex}meta{/tex}-directing substituents in aromatic substitution are given. Which one is most deactivating?

A

{tex} - \mathrm { COOH } {/tex}

{tex} - \mathrm { NO } _ { 2 } {/tex}

C

{tex} - \mathrm { C } \equiv \mathrm { N } {/tex}

D

{tex} - \mathrm { SO } _ { 3 } \mathrm { H } {/tex}

Explanation


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Q 21. Arrange the following in increasing order of stability

{tex} 5 < 4 < 3 < 1 < 2 {/tex}

B

{tex} 4 < 5 < 3 < 1 < 2 {/tex}

C

{tex} 1 < 5 < 4 < 3 < 2 {/tex}

D

{tex} 5 < 4 < 3 < 2 < 1 {/tex}

Explanation


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Q 22. What is the hybridisation state of benzyl carbonium ion ?

{tex} s p ^ { 2 }{/tex}

B

{tex} s p d ^ { 2 } {/tex}

C

{tex} s p ^ { 2 } d {/tex}

D

{tex} s p ^ { 3 } {/tex}

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Q 23. Nitrogen detection in an organic compound is carried out by Lassaigne's test. The blue colour formed corresponds to which of the following formulae?

A

{tex} \mathrm { Fe } _ { 3 } \left[ \mathrm { Fe } ( \mathrm { CN } ) _ { 6 } \right] _ { 2 } {/tex}

{tex} \mathrm { Fe } _ { 4 } \left[ \mathrm { Fe } ( \mathrm { CN } ) _ { 6 } \right] _ { 3 } {/tex}

C

{tex} \mathrm { Fe } _ { 4 } \left[ \mathrm { Fe } ( \mathrm { CN } ) _ { 6 } \right] _ { 2 } {/tex}

D

{tex} \mathrm { Fe } _ { 3 } \left[ \mathrm { Fe } ( \mathrm { CN } ) _ { 6 } \right] _ { 3 } {/tex}

Explanation

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Q 24. Homolytic fission of the following alkanes forms free radicals {tex} \mathrm { CH } _ { 3 } - \mathrm { CH } _ { 3 } , \mathrm { CH } _ { 3 } - \mathrm { CH } _ { 2 } - \mathrm { CH } _ { 3 } {/tex}, {tex} \left( \mathrm { CH } _ { 3 } \right) _ { 2 } \mathrm { CH } - \mathrm { CH } _ { 3 } , \mathrm { CH } _ { 3 } - \mathrm { CH } _ { 2 } - \mathrm { CH } _ { 2 } - \mathrm { CH } \left( \mathrm { CH } _ { 3 } \right) _ { 2 } {/tex} Increasing order of stability of the radicals is

A

{tex} \left( \mathrm { CH } _ { 3 } \right) _ { 2 } \dot { \mathrm { C } } - \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 } < \mathrm { CH } _ { 3 } - \dot { \mathrm { CH } } - \mathrm { CH } _ { 3 } {/tex} {tex} < \mathrm { CH } _ { 3 } - \dot { \mathrm { CH } } _ { 2 } < \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \dot \mathrm { C } {/tex}

{tex} \mathrm { CH } _ { 3 } -\dot \mathrm { CH } _ { 2 } < \mathrm { CH } _ { 3 } - \dot \mathrm { CHH } - \mathrm { CH } _ { 3 } {/tex} {tex} \left( \mathrm { CH } _ { 3 } \right) _ { 2 }\dot \mathrm { C } - \mathrm { CH } _ { 2 } - \mathrm { CH } _ { 3 } < \left( \mathrm { CH } _ { 3 } \right) _ { 3 }\dot \mathrm { C } {/tex}

C

{tex} \mathrm { CH } _ { 3 } - \dot\mathrm { CH } _ { 2 } < \mathrm { CH } _ { 3 } -\dot \mathrm { CH } - \mathrm { CH } _ { 3 } {/tex} {tex} <\left( \mathrm { CH } _ { 3 } \right) _ { 3 }\dot \mathrm { C } < \left( \mathrm { CH } _ { 3 } \right) _ { 2 }\dot \mathrm { C } - \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 } {/tex}

D

{tex} \left( \mathrm { CH } _ { 3 } \right) _ { 3 }\dot \mathrm { C } < \left( \mathrm { CH } _ { 3 } \right) _ { 2 } \dot\mathrm { C } - \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 } {/tex} {tex}< \mathrm { CH } _ { 3 } - \dot { \mathrm { CH } } - \mathrm { CH } _ { 3 } < \mathrm { CH } _ { 3 } - \dot { \mathrm { CH } } _ { 2 } {/tex}

Explanation


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Q 25. The compound insoluble in acetic acid is

A

Calcium oxide

B

Calcium carbonate

Calcium oxalate

D

Calcium hydroxide

Explanation

Calcium oxalate is insoluble in acetic acid, whereas calcium oxide, calcium carbonate and calcium hydroxide are soluble in acetic acid. The insolubility of calcium oxalate in acetic acid is due to its high lattice energy and low solvation energy.