Density is least for the halogen
Atomic radius trend….F<Cl<Br<I;
Density trend….F<Cl<Br<I;
IP trend….F>Cl>Br>I;
EN trend….F>Cl>Br>I;
Electron gain enthalpy trend….I<Br<F<Cl;
IP trend…..I-<Br-<F-<Cl-;
IP trend….F>Cl>Br>I>Cl->F->Br->I-
B.D.E….Cl2>Br2>F2>I2;
Reactivity and oxidizing power…..F2>Cl2>Br2>I2;
Hydration enthalpy…F->Cl->Br->I-;
MP and BP trend….F2<Cl2<Br2<I2; Due to increased strength of London dispersion forces;