Alkene | MCQs

Explanation

Hydration is the process of adding water (H₂O) to alkenes to form alcohols, usually in the presence of H₂SO₄ as a catalyst.

It follows Markovnikov's rule, where the –OH group attaches to the more substituted carbon.

Explanation

Ozonolysis is the reaction where ozone (O₃) breaks double bonds in alkenes to form ozonides.

This process is used to determine the position of double bonds in organic compounds.

Explanation

Alkenes are commonly known as Olefins due to their ability to form oily liquids when reacting with chlorine.

They are unsaturated hydrocarbons containing at least one carbon-carbon double bond (C=C).

Explanation

Ozonolysis splits the double bond and gives:

• CH₃CH₂COCH₃ (Butan-2-one)
• CH₃CHO (Acetaldehyde)

These products match the cleavage of 3-methyl-2-pentene at the double bond.

Explanation

Bayer's test (using dilute potassium permanganate) detects the presence of C=C double bonds in alkenes.

A positive test results in decolorization of the purple KMnO₄ solution.

Explanation

 Hydroxylation of alkene can be carried out by  alkaline KMnO4. 

Hydroxylation refers to the addition of two hydroxyl (OH) groups across a carbon-carbon double bond in an alkene.

Cold, dilute, alkaline potassium permanganate (KMnO4) is a common reagent used for this reaction.

It reacts with the alkene to form a vicinal diol (a molecule with two hydroxyl groups on adjacent carbon atoms). 

Explanation

Reactivity in organic compounds is largely determined by the presence of multiple bonds.

Ethyne has a triple bond, which is the most reactive bond due to the greater electron density and availability for participation in reactions.

Explanation

Alkenes are a class of unsaturated hydrocarbons that contain one or more carbon-carbon double bonds (C=C).

This double bond is the defining feature of alkenes.

It makes them more reactive than saturated hydrocarbons (alkanes).

Explanation

Ozonolysis cleaves the double bond in 3-Ethyl-2-pentene, forming two carbonyl compounds.

The double bond is between C2 and C3:

CH3–CH=CH–CH(CH2CH3)–CH3

On ozonolysis, it breaks at the double bond, yielding:

- Ethanal (CH3CHO) from the CH= part

- 3-Pentanone (CH3COCH2CH2CH3) from the rest

Explanation

The addition of HBr to isobutylene follows Markovnikov's rule, which results in the formation of tert-butyl bromide as the major product.