Decolorization of KMnO₄ solution takes place when it reacts with ethene. The final product of  this reaction which is used as an anti-freeze is:

Ethylene glycol

The correct answer is option 1. Ethylene glycol.

The decolorization of potassium permanganate (KMnOâ‚„) solution when it reacts with ethene (ethylene) results in the formation of ethylene glycol. KMnOâ‚„ is a strong oxidizing agent and reacts with alkenes to form diols (compounds with two hydroxyl groups).

Here is the reaction:

In this reaction, ethene (CHâ‚‚=CHâ‚‚) reacts with KMnOâ‚„ in the presence of water to form ethylene glycol (HOCHâ‚‚CHâ‚‚OH). Ethylene glycol is commonly used as an antifreeze in cooling and heating systems.

Therefore, the final product of this reaction, which is used as an antifreeze, is: Ethylene glycol.

Hydroxylation of ethene takes place in the presence of cold KMnO₄​ to form Ethylene glycol.