Consider the given reaction for preparation of alkyne. (Fritsch reaction).

Anti group will migrate because of less steric hindrance.
Rate of reaction when the halide ion:

Options

A. `I^(Theta) gt Cl^(Theta) gt Br^(Theta) gt F^(Theta)`
B. `I^(Theta) gt Br^(Theta) gt Cl^(Theta) gt F^(Theta)`
C. `F^(Theta) gt Cl^(Theta) gt Br^(Theta) gt I^(Theta)`
D. `F^(Theta) gt Br^(Theta) gt Cl^(Theta) gt I^(Theta)`

Answer

B

Explanation

Good leaving group