Match the following columns.
 

	Column I (Properties of defects)		Column II (Types of defects)
A	It maintains electrical neutrality	1	Vacancy defects
B	It is also known as dislocation defect	2	Interstitial defect
C	This intrinsic defect results in decrease in density in non-ionic solids.	3	Frenkel defect
D	This defect increases the density in non-ionic solids.	4	Schottky defect

• Vacancy defect: When an atom is not present at their lattice sites, then that lattice site is vacant and it creates a vacancy defect. Due to this, the density of a substance decreases.
• Interstitial defect: It is a defect in which an atom or molecule occupies the intermolecular spaces in crystals. In this defect, the density of the substance increases.
• Frenkel defect: In ionic solids generally, the smaller ion (cation) moves out of its place and occupies an intermolecular space. In this case, a vacancy defect is created on its original position and the interstitial defect is experienced at its new position. It is also known as dislocation defect.
• Schottky defect: This kind of vacancy defects is found in Ionic Solids. But in ionic compounds, we need to balance the electrical neutrality of the compound so an equal number of anions and cations will be missing from the compound.

$\therefore \mathrm{A}\to 4;\mathrm{B}\to 3;\mathrm{C}\to 1;\mathrm{D}\to 2$