Examine the given defective crystal
`{:(A^(+), B^(-),A^(+),B^(-),A^(+)),(B^(-), O,B^(-), A^(+),B^(-)),(A^(+),B^(-),A^(+),O,A^(+)),(B^(-),A^(+),B^(-),A^(+),B^(-)):}`
Answer the following question :
(i) What type of stoichiometric 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) Density of the crystal decreases
(iii) This type of defect in shown by ionic compounds in which the ions have high coordination number and there is small difference in the size and anions.