Question

The correct order of electron gain enthalpy with negative sign of f,cl,br and i having atomic number 9,17,35,53 respectively is

Answer 1

These are the group 17 elements arranged in order as we move down the group. Thus the correct order of decreasing electronegativity will be

Cl

F

Br

I

The electronegativity decreases as we move down the group. But the electron gain enthalpy of Cl is more than that of F because of the small size of F which leads to repulsion in the electrons.