The perovskite structure is common for mixed metal oxides and halides. In this structure A and B are cations of different sizes and X is either an oxide or halide. the structure is built up of a simple cube of A cations with anions in the center of the faces. The B cation occupies the Oh hole in the center of the cube. the solid formed by K+, Ni2+, and F- adopts this structure. a)What is the stoichiometry of this solid? b) Which cation goes where? Why? Hint: Ni2+ is smaller than K+