Which of the following statements is incorrect for ethylene dichloride and ethylidene chloride?

Both of these yield same product on treatment with aqueous KOH solution

The correct answer is option 3. Both of these yield same product on treatment with aqueous KOH solution.

Let us break down the reactions and the reasoning to understand why the given options correct or incorrect.

Structures: The structures of the given compounds are 

1. These are structural isomers

Structural Isomers: Compounds with the same molecular formula but different structural arrangements.

Ethylene dichloride and ethylidene chloride both have the formula \(C_2H_4Cl_2\) but different structures. So, this statement is correct.

2. Both of these yield the same product on reaction with alcoholic KOH solution

Alcoholic \(KOH\) is a strong base and promotes elimination \((E_2)\) reactions. Ethylene dichloride undergoes dehydrohalogenation (removal of \(HCl\)) to form vinyl chloride.

Ethylidene chloride (1,1-dichloroethane) on reaction with 1 mole of \(KOH\) undergoes dehydrohalogenation reaction to give vinyl chloride.

3. Both of these yield the same product on treatment with aqueous \(KOH\) solution

Aqueous \(KOH\) usually favors substitution reactions due to the presence of water.

Ethylene dichloride (1,2-dichloroethane) with aqueous KOH results in the formation of ethylene glycol.

Ethylidene chloride (1,1-dichloroethane) with aqueous KOH results in the formation of acetaldehyde.

These reactions do not lead to the same product, so this statement would actually be incorrect.

4. Both of these yield the same product on reduction

Reduction with hydrogen or other reducing agents typically results in the replacement of chlorine atoms with hydrogen.

Ethylene dichloride (1,2-dichloroethane) on reduction results in formation ethane. Ethylidene chloride (1,1-dichloroethane) on reduction also results in ethane.

Thus, the incorrect statement is 3. Both of these yield the same product on reaction with aqueous KOH solution