The incorrect statement about the imperfections in solids is .... .

Explain the metal excess defect.

The correct statement regarding defects in solids is

$A$ metallic solid undergoes Frenkel defect. Its original mass,volume and density are $M_0$,$V_0$ and $D_0$ respectively. After Frenkel defect the mass,volume and density are $M$,$V$ and $D$ respectively. The variations of $M$,$V$ and $D$ after Frenkel defect are

Assertion: In an ionic solid $(MX)$,Schottky defect contains an equal number of cations and anions.
Reason: Equal number of vacancies are present for both cations and anions.

The correct statement among the following,regarding defects in solids is:
$(1)$ Frenkel defect is favored by small difference in the sizes of cation and anion.
$(2)$ Frenkel defect is a metal excess defect.
$(3)$ Trapping of electron in the lattice leads to formation of $F$-centres.
$(4)$ Schottky defect has no effect on the physical property of solids.