Question

which of the following will have the most negative and least negative electron gain enthalpy respectively pscl and F​

Answer 1

NEGATIVE ELECTRON GAIN ENTHALPY :

It's the amount of energy released when an electron is added to its valence shell .It increases across the period from left to right because from left to right the effective nuclear charge increase and atomic size decrease and more amount of energy will released from a small atom in compare to large atom, there for down the group Electron Gain Enthalpy decrease as the atomic size increase.

(Fluorine have highest Electron Gain Enthalpy in the periodic table)

So, Fluorine (F) have most Electron Gain Enthalpy and Phosphorus (P) have least.

F > Cl > S > P