The answer is; D
Enthalpy is the system’s internal energy ( considering the product of its pressure and volume). When the enthalpy is negative, it means that the products have a lower energy level than the reactants - meaning the system has dispensed some energy into the environment.
Electron affinity for fluorine is than chlorine most likely , due to the electron repulsion that occur between the electron where n= 2 . the elements in the second period have such small electron clouds that electron repulsion is greater than that of the rest of the family.
Answer,
For example, silver ion can be precipitated with hydrochloric acid to yield solid silver chloride. Because many cations will not react with hydrochloric acid in this way, this simple reaction can be used to separate ions that form insoluble chlorides from those that do not.
