Match the following
1-a,2-a,3-a,4-a
Perfect crystals are not good conductors of electricity as ions are rigidly placed in their lattice points. Either extra ions, or free e-s or voids act as electrical carriers. So defects which increase either ions, electrons or voids (holes) can increase the conductivity of the crystal.
In Schottky defect both cations and anions miss from their lattice points creating vacancies. Schottky defect is a vacancy defect. Due to their vacancies conduction increases.
In Interstitial defect, particles occupy the interstitial sites. Due to these extra particles, conductivity increases.
In frenkel defect, particles leave their lattice points creating vacancies and occupies interstitial sites (voids). So frenkel defect is both vacancy defect and interstitial defect. Due to the particles in voids and presence of vacancies conduction increases in frenkel defect.