Question 12 is based on the following reading passage.
In electrides, the anions (negative ions) are completely replaced by electrons, which are trapped in naturally formed cavities within a framework of regularly stacked cations (positive ions). Unlike other types of anions, anionic electrons do not behave as if they were simple charged spheres. The properties of an electridedepend largely on the distance between the cavities that hold trapped electrons. When the trapped electrons are far apart, they do not interact strongly, and so behave somewhat like an array of isolated negative charges. When they are closer together, they begin to display properties associated with large ensembles of identical particles. When they are still closer, the ensemble properties dominate and the electrons "delocalize".
12. It can be inferred from the passage that an electride behaves most like a normal ionic crystal when the electride has which of the following features?
(A) The anionic cavities are widely separated.
(B) All of the trapped electrons are able to delocalize.
(C) The trapped electrons are liberated by impinging photons.
(D) The ions are tightly packed together.
(E) Most of the cations have lost their electrical charge.
答案：A
