ESE 2021 Technical Quiz || crystal structures and defects

For simple cubic crystal structure, packing efficiency is:

In Face-Centred Cubic structure (FCC), what number of atoms is present in each unit cell?

Schottky defect is an example of

In a crystal lattice, the defect created by movement of ion from its original position to interstitial position is:

For BCC, effective number of atoms per unit are: