Potassium permanganate reagent is used for :

1. Oxidation of primary alcohol to carboxylic acid.
2. Oxidation of primary alcohol to aldehyde.
3. Bromination of phenol to 2,4,6-tribromophenol.
4. Dehydration of propan-2-ol to propene.

The proposed mechanism for hydration of ethene to yield ethanol is as follows:

The wrong step in the above mechanism is:

1. Step 1

2. Step 2

3. Step 3

4. Both steps 2 and 3