Though fluorine is more electronegative than chlorine yet `BF_3` is a weaker lewis acid than `BCl_3`, why ?

Why HF is a weaker acid than HCl ?

Fluorine atom is more electronegative than iodine atom, yet HF is weaker acid than HI. Justify.

Why formaldehyde is more reactive than Acetone ?

HI is stronger /weaker acid than HCl.

Why ICI is more reactive than I_2 ?

BF_3 acts as a Lewis acid. Why ?

Explain the following : HF is a weaker acid than HI.

Although fluorine is much more electronegative than hydrogen yet the dipole moment of NF3(0.24D) is much lower than that of NH3(1.46D). Explain.

Why alkenes are more reactive than alkanes?