Many metals have cubic crystal structures, which exhibit high symmetry. This fact facilitates the development of slip systems, which facilitate the...

Many metals have cubic crystal structures, which exhibit high symmetry. This fact facilitates the development of slip systems, which facilitate the movement of dislocations under mechanical stress. Regarding the crystal structure of metals and their defects, classify V for true statements and F for false statements:

( ) Dislocations are defects in the crystal structure caused by a misalignment of atoms. The amount of dislocations in a metallic material is related to its mechanical properties.
( ) Vacancies are a type of defect characterized by the absence of atoms in the crystal structure. The amount of vacancies decreases with increasing temperature.
( ) Impurities are crystal defects characterized by the presence of foreign atoms in the metal's composition. The presence of these defects worsens the mechanical properties of metals.
( ) Impurities can be of two types: substitutional, when they replace an atom in the material, or interstitial, when they occupy the interstitial sites in the crystal structure.
a) V - F - F - V.
b) V - F - V - F.
c) F - V - V - F.
d) F - V - F - V.