The incorrect statement about the imperfections in solids is

Frenkel Defect: This defect is shown by ionic solids. The smaller ion (usually cation) is dislocated from its normal site to an interstitial site. It creates a vacancy defect at its original site and an interstitial defect at its new location. Frenkel defect is also called dislocation defect. It does not change the density of the solid. In all other defects there is a change in the density.

In Schottky defect equal number of cation and anion are missing from their position so, it decreases the density of the substance.

In Interstitial defect extra atoms are present at interstitial position so, it increases the density of the substance.

Due to vacancy defect density of the substance will decrease. since atoms are missing from their positions.