Which of the following processes listed below represents the experiment for measureing an ionization energy?
(E--> represents a nuetral element, "m"- represents a metal cation; and X represents a nonmental anion)
A. MX (g) + energy --> M^n+^ (g) + X^n-^ (g)
B. E(g) + energy--> E^+^(g) + e^-^
C. X-X (g) + energy --. 2 X (g)
D. E(g) + e^-^ --> E-(g) + energy
E. None of these