CBSE Class 12-science Answered

Point defect:

When the deviations or irregularities exist from the ideal arrangement around a point or an atom in a crystalline substance, the defect is called point defect.

 Line defect:

When the deviation from the ideal arrangement exists in the entire row of lattice points, the defect is called line defect.

 Dislocation:

 Planar defects:

Planar defects are interfaces between homogeneous regions of the material. Planar defects include grain boundaries, stacking faults and external surfaces.