The correct statement(s) regarding defects in solid is (are): 

Those defects that do not disturb the stoichiometry of the solid, they maintain the electrical neutrality of ionic solid. Frenkel defects does not disturb the stoichiometry of the solid and known as dislocation defects.

Schottky defect decreases the density of the substance. The anionic sites occupied by unpaired electrons are called F-centres.