Question

1. what is circled in the model of atoms in crystal structure below?

options:
a dislocation
a vacancy defect
an interstitial defect
a substitutional defect

Explanation:

To determine the circled part, we analyze each option:

• A dislocation involves a misalignment of atoms in a crystal lattice (not a single empty site).
• A vacancy defect is a missing atom in the regular crystal lattice, which matches the empty space (circled) among the green atoms (representing a regular lattice with a missing atom).
• An interstitial defect is an extra atom in the interstitial space (not an empty site).
• A substitutional defect is when one atom is replaced by another (not an empty site).

So the circled part is a vacancy defect.

Answer:

B. a vacancy defect