Which reaction should be used to convert propene into an alkyl halide?
addition
condensation
elimination
substitution

The correct answer is addition reaction.

Explanation:

For the given options:

Option 1: Addition

Addition reaction is defined as the reaction where more number of atoms are added to the given compound. No atom is lost during this type of reaction.  

Option 2: Condensation

Condensation reaction is defined as the reaction in which two substances combine to form a large molecule with the release of small molecules such as etc.

Option 3: Elimination

Elimination reaction is defined as the reaction in which two or more substituents are removed from a large molecule.

Option 4: Substitution

Substitution reaction is defined as the reaction in which one atom replaces the other atom from the compound.

In the question, it is asked that the conversion of propene to alkyl halide takes place. This conversion takes place due to addition reaction.

The equation for the conversion of propene to alkyl halide follows:

Thus, the correct answer is addition reaction.

substitution is the answer in this case