Reactivity order of the following alkyl halides towards dehydrohalogenation is:

Choose the correct answer from the options given below:

(A) > (B) > (C) > (D)

The correct answer is Option (1) → (A) > (B) > (C) > (D)
Dehydrohalogenation of alkyl halides occurs mainly through the E2 elimination reaction in the presence of a base. The rate of elimination largely depends on the leaving group ability of the halogen.

The leaving group ability of halides follows the order:

I⁻ > Br⁻ > Cl⁻ > F⁻

This is because:

• Iodide ion is the largest and most stable, so it leaves easily.

• Fluoride ion is the smallest and strongly bonded to carbon, so it leaves with difficulty.

In the given compounds, the carbon skeleton is the same; only the halogen changes:

• (A) Alkyl iodide

• (B) Alkyl bromide

• (C) Alkyl chloride

• (D) Alkyl fluoride

Thus, the ease of elimination follows the leaving group ability:

R–I > R–Br > R–Cl > R–F

Therefore, the reactivity order towards dehydrohalogenation is:

(A) > (B) > (C) > (D).