HF is the least acidic in halogen acids but still it is most reactive in halogen acids .Why??

Both F and H are small and hence overlapping is good compared to HCl, HBr and HI. Where as HI is the most acidic due to a largely mismatch in overlapping of bonding orbitals due to large size of Iodine. Due to fittest lattice in case of HF, it does not dessociates completely.But the dessociated HF gives fluoride ion which is verry small in size compared to other haloges and all halide ions have 8 electrons in there valance shell. Fluoride being smallest, the inter electronic repulsion is the most due to 8 electrons in a very small orbital ans hence most reactive.