NEET Organic Chemistry: Some Basic Principles and Techniques PYQ practice sheet

17 previous-year NEET Chemistry questions from Organic Chemistry: Some Basic Principles and Techniques, newest papers first. Organic Chemistry: Some Basic Principles and Techniques carries 21 of the Chemistry questions in NEET 2020 to 2026, so this is a good place to test yourself after revising the chapter. Marking: +4 correct, −1 wrong.

1. 1.

   RE-NEET 2026

   The following carbocation is stabilized by the interaction of the empty $p$ orbital with Figure: the $1$-phenylethyl carbocation, $\mathrm{C_6H_5-\overset{+}{C}H-CH_3}$ (a benzene ring attached to a positively charged carbon bearing a methyl group).

   • (A)
     filled $\sigma$ and filled $\pi$ orbitals
   • (B)
     empty $\sigma$ and empty $\pi^*$ orbitals
   • (C)
     empty $\sigma^*$ and empty $\pi^*$ orbitals
   • (D)
     empty $\sigma^*$ and filled $\pi$ orbitals
2. 2.

   RE-NEET 2026

   The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is

   • (A)
     methionine
   • (B)
     threonine
   • (C)
     leucine
   • (D)
     serine
3. 3.

   NEET 2026

   The pair of molecules that are metamers among the following is:

   • (A)
     $\mathrm{CH_3CH_2CH_2OH}$ and $\mathrm{CH_3-CH(OH)-CH_3}$
   • (B)
     $\mathrm{CH_3-CO-CH_3}$ (propanone) and $\mathrm{CH_3CH_2-CHO}$ (propanal)
   • (C)
     $\mathrm{CH_3CH_2CH_2CH_2CH_3}$ and $\mathrm{(CH_3)_2CHCH_2CH_3}$
   • (D)
     $\mathrm{CH_3OCH_2CH_2CH_3}$ and $\mathrm{CH_3CH_2OCH_2CH_3}$
4. 4.

   NEET 2026

   The correct IUPAC name of the following compound is: The structure is a seven-carbon chain $\mathrm{CH_3-CH_2-CH-CH_2-CH-CH_2-CH_3}$ with an ethyl group ($\mathrm{CH_3CH_2-}$) on the third carbon and a methyl group on the fifth carbon.

   • (A)
     3-ethyl-5-methylheptane
   • (B)
     3-methyl-5-ethylheptane
   • (C)
     3,5-diethylhexane
   • (D)
     2,4-diethylhexane
5. 5.

   NEET 2026

   Two products X and Y are formed in the following reaction sequence. Benzene is methylated with $\mathrm{CH_3Cl}$/anhydrous $\mathrm{AlCl_3}$ to give toluene (W), which on nitration gives the ortho and para nitrotoluenes (X and Y). The suitable method that can be used for the separation of products X and Y is:

   • (A)
     Fractional distillation
   • (B)
     Continuous extraction
   • (C)
     Differential extraction
   • (D)
     Sublimation
6. 6.

   NEET 2026

   During Lassaigne's test, the elements present in an organic compound are converted from:

   • (A)
     Ionic form to covalent form
   • (B)
     Covalent form to ionic form
   • (C)
     Ionic form to ionic form
   • (D)
     Covalent form to covalent form
7. 7.

   NEET 2024

   A compound with a molecular formula of $\mathrm{C_6H_{14}}$ has two tertiary carbons. Its IUPAC name is:

   • (A)
     2,3-dimethylbutane
   • (B)
     n-hexane
   • (C)
     2,2-dimethylbutane
   • (D)
     2-methylpentane
8. 8.

   NEET 2024

   On heating some solid substance change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as:

   • (A)
     Crystallization
   • (B)
     Sublimation
   • (C)
     Distillation
   • (D)
     Chromatography
9. 9.

   NEET 2024

   The most stable carbocation among the following is:

   • (A)
     
   • (B)
     
   • (C)
     
   • (D)
     
10. 10.

    NEET 2023

    In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with $\mathrm{Fe^{3+}}$ due to the formation of -

    • (A)
      $[\mathrm{Fe(SCN)}]^{2+}$
    • (B)
      $\mathrm{Fe_4[Fe(CN)_6]_3\cdot xH_2O}$
    • (C)
      $\mathrm{NaSCN}$
    • (D)
      $[\mathrm{Fe(CN)_5NOS}]^{4-}$
11. 11.

    NEET 2023

    The number of $\sigma$ bonds, $\pi$ bonds and lone pair of electrons in pyridine, respectively are:

    • (A)
      12, 2, 1
    • (B)
      11, 2, 0
    • (C)
      12, 3, 0
    • (D)
      11, 3, 1
12. 12.

    NEET 2022

    Which compound amongst the following is not an aromatic compound?

    • (A)
      
    • (B)
      
    • (C)
      
    • (D)
      
13. 13.

    NEET 2022

    The Kjeldahl's method for the estimation of nitrogen can be used to estimate the amount of nitrogen in which one of the following compounds?

    • (A)
      an azo compound (two aryl rings joined by $-\mathrm{N=N-}$)
    • (B)
      nitrobenzene ($-\mathrm{NO_2}$ substituted benzene)
    • (C)
      pyridine (a six-membered aromatic ring containing a ring nitrogen)
    • (D)
      aniline ($-\mathrm{NH_2}$ substituted benzene)
14. 14.

    NEET 2022

    The correct IUPAC name of a hexane chain bearing a chloro substituent at C-2, a bromo substituent at C-6 and a hydroxyl group at C-4 (numbered so that the principal characteristic group, -ol, receives the lowest possible locant) is:

    • (A)
      6-bromo-4-methyl-2-chlorohexan-4-ol
    • (B)
      1-bromo-5-chloro-4-methylhexan-3-ol
    • (C)
      6-bromo-2-chloro-4-methylhexan-4-ol
    • (D)
      1-bromo-4-methyl-5-chlorohexan-3-ol
15. 15.

    NEET 2021

    The compound which shows metamerism is :

    • (A)
      $\mathrm{C_3H_6O}$
    • (B)
      $\mathrm{C_3H_8O}$
    • (C)
      $\mathrm{C_4H_{10}O}$
    • (D)
      $\mathrm{C_5H_{12}}$
16. 16.

    NEET 2021

    The correct structure of 2,6-Dimethyl-dec-4-ene is :

    • (A)
      
    • (B)
      
    • (C)
      
    • (D)
      
17. 17.

    NEET 2020

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

    • (A)
      $-I$ effect of $-\mathrm{CH_3}$ groups
    • (B)
      $+R$ effect of $-\mathrm{CH_3}$ groups
    • (C)
      $-R$ effect of $-\mathrm{CH_3}$ groups
    • (D)
      Hyperconjugation