Hydrocarbons Test

Result

Hydrocarbons Test - 6

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

The lowest alkene which is capable of exhibiting geometrical isomerism is

A
1-butene

B
2-pentene

C
2-butene

D
2,3-dimethylbutene

Solution

Alkenes exhibit geometrical isomerism due to restricted rotation around the caron-carbon double bond. However, the alkene molecule should not have the same groups attached to the double bonded carbon atom.
Hence, but-2-ene (CH₃CH=CHCH₃) is the smallest alkene to exhibit geometrical isomerism.
Question 2
1 / -0

The compound which reacts with HBr-obeying Markovnikoff's rule is

A
CH₂=CH₂

B
CH₃CH=CHCH₃

C
CH₃CH₂CH=CHCH₂CH₃

D
(CH₃)₂C=CH₂

Solution

Only unsymmetrical alkenes give Markovnikoff's rule. Hence, the compound which reacts with HBr-obeying Markovnikoff's rule is (CH₃)₂C=CH₂.
Question 3
1 / -0

The IUPAC name of the compound having the formula CH≡C-C=CH₂ is

A
1-Butyne-3-ene

B
But-1-yn-3-ene

C
But-3-yn-1-ene

D
3-Butene-1-yne

Solution

The IUPAC name of the compound having the formula CH≡C-C=CH₂ is But-3-yn-1-ene.
According to the IUPAC rules, the double bond gets priority over the single bond and is assigned the lower location.
Question 4
1 / -0

Which of the following does not dissolve in conc. H₂SO₄?

A
CH₂=CH₂

B
CH₃-C≡C-CH₃

C
CH₃CH₂C≡CH

D
CH≡CH

Solution

Unsaturated hydrocarbons dissolve in conc. H₂SO₄ by electrophilic addition reaction which proceeds through the formation of a carbocation intermediate (Markovnikov addition). Hence, the solubility of the hydrocarbons depends on the stability of the carbocation formed.
In case of CH≡CH, a vinyl carbocation would be formed which is highly unstable due to a greater percentage of s-character in the positively charged, sp² hybridised 'C'. Hence, C₂H₂ is not soluble in H₂SO₄.
Ethene gives more stable carbocation with electron repelling alkyl group (-CH₃) attached to the positively charged, sp³ hybridised C. Therefore, it (ethene) is likely to be dissolved. Alkynes, other than ethyne, form vinyl carbocations having electron repelling alkyl groups and thus, they are more stable than vinyl carbocations formed in ethyne and are sparingly soluble in conc. H₂SO₄.