The correct answer is (D) : Vacancy defect increases the density of the substance.
When constituent particles occupy the interstitial location, interstitial defect arises. This increases the density of substance. Frenkel defect occurs when constituent particles occupy the interstitial site.
It creates vacancy defect at original and interstitial defect at the new location. It does not change the density of crystal.
Due to vacancy defect density of the substance will decrease.
Consider the following sequence of reactions : 
Molar mass of the product formed (A) is ______ g mol\(^{-1}\).
The magnitude of heat exchanged by a system for the given cyclic process ABC (as shown in the figure) is (in SI units):

Any irregularity in the pattern of crystal arrangement in a solid lattice is called imperfection in solids. The occurrence of defects takes place when crystallization (the process of formation of crystals) occurs at a very fast or at an intermediate rate.
Basically, defects fall out in two forms:
When the irregularities exist from the ideal arrangement around a point or an atom in solids, the defect is known as a point defect. Types of point defects are:
When the deviation from the ideal arrangement exists in the entire row of lattice points, the defect is called line defect.