Examine the given defective crystal and
`{:(A^(+),B^(-),A^(+),B^(-),A^(+)),(B^(-),0,B^(-),A^(+),B^(-)),(A^(+),B^(-),A^(+),0,A^(+)),(B^(-),A^(+),B^(-),A^(+),B^(-)):}`
Answer the following questions :
(i) What type of stoichiometirc defect is shown by the crystal ?
(ii) How is the density of the crystal affected by this defect ?
(iii) What type of ionic substances show such defect ?

Explanation

(i) Schottky defect.
(ii) Decreases.
(iii) Alkali metal halides/Ionic substances having almost similar size of cations and anions (NaCl/KCl).