NEET Hydrocarbons PYQ practice sheet

13 previous-year NEET Chemistry questions from Hydrocarbons, newest papers first. Hydrocarbons 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

   Given below are two statements : Statement I : $trans$-But-2-ene upon treatment with $\mathrm{Br_2}$ in $\mathrm{CCl_4}$ gives the product shown as the first Newman projection (viewed along the C2-C3 bond): front carbon with $\mathrm{Br}$ (down), $\mathrm{H}$ (upper left), $\mathrm{Me}$ (upper right); rear carbon with $\mathrm{Br}$ (up), $\mathrm{H}$ (lower left), $\mathrm{Me}$ (lower right). Statement II : $cis$-But-2-ene upon treatment with alkaline $\mathrm{KMnO_4}$ gives the product shown as the second Newman projection: front carbon with $\mathrm{Me}$ (down), $\mathrm{H}$ (upper left), $\mathrm{OH}$ (upper right); rear carbon with $\mathrm{OH}$ (up), $\mathrm{H}$ (lower left), $\mathrm{Me}$ (lower right). In the light of the above statements, choose the most appropriate answer from the options given below.

   • (A)
     Both Statement-I and Statement-II are correct
   • (B)
     Both Statement-I and Statement-II are incorrect
   • (C)
     Statement-I is correct but Statement-II is incorrect
   • (D)
     Statement-I is incorrect but Statement-II is correct
2. 2.

   RE-NEET 2026

   Consider the following reaction sequences and choose the correct option. Scheme: $\mathrm{Ph{-}C{\equiv}C{-}Me}$ is treated with $\mathrm{Na/liq.\ NH_3}$ to give L, and with $\mathrm{H_2, Pd/C}$ (Lindlar's catalyst) to give K. L is treated with $\mathrm{HBr}$ in the presence of benzoyl peroxide to give N, and K is treated with $\mathrm{HBr}$ to give M.

   • (A)
     M and N are stereoisomers
   • (B)
     M and N are geometrical isomers
   • (C)
     K and L are enantiomers
   • (D)
     K and L are geometrical isomers
3. 3.

   RE-NEET 2026

   Among the following, the compound having conjugated double bonds is

   • (A)
     hepta-1,6-diene
   • (B)
     hepta-1,4-diene
   • (C)
     hepta-1,5-diene
   • (D)
     hepta-1,3-diene
4. 4.

   NEET 2024

   Given below are two statements: Statement I: The boiling point of three isomeric pentanes follows the order n-pentane > isopentane > neopentane. Statement II: When branching increases, the molecule attains a shape of sphere. This results in smaller surface area for contact, due to which the intermolecular forces between the spherical molecules are weak, thereby lowering the boiling point. In the light of the above statements, choose the most appropriate answer from the options given below:

   • (A)
     Both Statement I and Statement II are incorrect.
   • (B)
     Both Statement I and Statement II are correct.
   • (C)
     Statement I is correct but Statement II is incorrect.
   • (D)
     Statement I is incorrect but Statement II is correct.
5. 5.

   NEET 2024

   For the given reaction: (1,2-dicyclohexylethene, cyclohexyl$-\mathrm{CH=CH-}$cyclohexyl) is treated with $\mathrm{KMnO_4/H^+}$ to give 'P' (major product). 'P' is

   • (A)
     
   • (B)
     
   • (C)
     
   • (D)
     
6. 6.

   NEET 2023

   Weight (g) of two moles of the organic compound, which is obtained by heating sodium ethanoate with sodium hydroxide in presence of calcium oxide is :

   • (A)
     18
   • (B)
     16
   • (C)
     32
   • (D)
     30
7. 7.

   NEET 2023

   Consider the following compounds/species: i. Naphthalene (two fused benzene rings) ii. Cyclopentadienyl anion (five-membered ring with two double bonds and a carbanion bearing a lone pair) iii. Cyclobutadiene (four-membered ring with two double bonds) iv. Cyclopropenyl anion (three-membered ring with one double bond and a carbanion with a lone pair) v. Cyclopropenyl cation (three-membered ring with one double bond and a positive charge) vi. Cyclooctatetraene (eight-membered ring with four double bonds) vii. Anthracene (three linearly fused benzene rings) The number of compounds/species which obey Huckel's rule is ______.

   • (A)
     5
   • (B)
     4
   • (C)
     6
   • (D)
     2
8. 8.

   NEET 2022

   Compound X on reaction with $\mathrm{O_3}$ followed by $\mathrm{Zn/H_2O}$ gives formaldehyde and 2-methylpropanal. The compound X is:

   • (A)
     Pent-2-ene
   • (B)
     3-Methylbut-1-ene
   • (C)
     2-Methylbut-1-ene
   • (D)
     2-Methylbut-2-ene
9. 9.

   NEET 2021

   Dihedral angle of least stable conformer of ethane is :

   • (A)
     $60^\circ$
   • (B)
     $120^\circ$
   • (C)
     $0^\circ$
   • (D)
     $180^\circ$
10. 10.

    NEET 2021

    The major product of the following chemical reaction is : $\mathrm{(CH_3)_2CH-CH{=}CH_2 + HBr \xrightarrow{(C_6H_5CO)_2O_2} {?}}$ The reactant is 3-methylbut-1-ene.

    • (A)
      
    • (B)
      
    • (C)
      
    • (D)
      
11. 11.

    NEET 2021

    $\mathrm{CH_3CH_2COO^{-}Na^{+} \xrightarrow[\text{Heat}]{NaOH,\ ?} CH_3CH_3 + Na_2CO_3}$. Consider the above reaction and identify the missing reagent/chemical.

    • (A)
      $\mathrm{B_2H_6}$
    • (B)
      $\mathrm{CaO}$
    • (C)
      Red Phosphorus
    • (D)
      $\mathrm{DIBAL\text{-}H}$
12. 12.

    NEET 2020

    Which of the following alkane cannot be made in good yield by Wurtz reaction?

    • (A)
      n-Hexane
    • (B)
      2,3-Dimethylbutane
    • (C)
      n-Heptane
    • (D)
      n-Butane
13. 13.

    NEET 2020

    An alkene on ozonolysis gives methanal as one of the product. Its structure is :

    • (A)
      
    • (B)
      
    • (C)
      
    • (D)