BoardChemistry

Hydrocarbons

5 Board Chemistry previous year questions on Hydrocarbons — options free on every question; 1 include the answer & explanation free, the rest unlock with PYQ Pass.

Q1 FREE PREVIEW
PYQ

Given below are two statements :
Statement (I): Neopentane forms only one monosubstituted derivative.
Statement (II): Melting point of neopentane is higher than n-pentane
In the light of the above statements, choose the most appropriate answer from the options given below

a

Statement I is correct but Statement II is incorrect

b

Both Statement I and Statement II are correct

c

Both Statement I and Statement II are incorrect

d

Statement I is incorrect but Statement II is correct

✓ Correct answer: b)

Both Statement I and Statement II are correct

Explanation
  • I true: Neopentane, C(CH₃)₄, is highly symmetric; all 12 hydrogens are equivalent → only one monosubstituted derivative.

  • II true: Its high symmetry improves packing, giving a higher melting point than n-pentane.
    Thus both statements are correct(B)

Q2
PYQ

Baeyer's reagent is :

[Re-NEET 2024]

a

acidic potassium permanganate solution

b

acidic potassium dichromate solution

c

cold, dilute, aqueous solution of potassium permanganate

d

hot, concentrated solution of potassium permanganate

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Q3
PYQ

The incorrect statements regarding geometrical isomerism are :
(A) Propene shows geometrical isomerism.
(B) Trans isomer has identical atoms/groups on the opposite sides of the double bond.
(C) Cis-but-2-ene has higher dipole moment than trans-but-2-ene.
(D) 2-methylbut-2-ene shows two geometrical isomers.
(E) Trans-isomer has lower melting point than cis isomer.

Choose the correct answer from the options given below

a

(B) and (C) Only

b

(C), (D) and (E) Only

c

(A) and (E) Only

d

(A), (D) and (E) Only

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Q4
PYQ

Identify the incorrect statement

(Memory Based JEE Mains 22/01/2025 ,Shift -1)

a

MP of Cis-2-butene is greater than trans-2-butene

b

But-2-ene can have two geometrical isomers

c

DP moment of Cis-2-butene is greater than trans-2-butene

d

In trans isomers identical groups are opposite in opposite direction

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Q5
PYQ

Identify the incorrect statement

(Memory Based JEE Mains 22/01/2025 ,Shift -1)

a

MP of Cis-2-butene is greater than trans-2-butene

b

But-2-ene can have two geometrical isomers

c

DP moment of Cis-2-butene is greater than trans-2-butene

d

In trans isomers identical groups are opposite in opposite direction

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