Which among the following elements will have a positive electron gain enthalpy?
The correct option is C N
Electron gain enthalpy is defined as the change in energy (in kJ/mol) of an isolated gaseous atom when an electron is added to the outermost shell of the atom to form a negative ion.
Nitrogen has a stable half filled electronic configuration. So, even though it is a non-metal, energy is required for the addition of extra electron i.e, N has a positive electron gain enthalpy.