Why the behaviour of fluorine is different from other halogens ?

Tracheids differ from other tracheary elements in

Why does the reactivity of nitrogen differ from the phosphorus ?

Why is fluorine a very reactive halogen ?

Why are human beings which look so different from each other in terms of size. Colour and looks are said to be belonging to the same species?

Why is that drift velociy is different from the velocity of electrons between collisions?

Meiotic division during oogenesis is different from that in spermatogenesis. Explain how and why?

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?