Identify the type of defect in brass alloy.

Iron crystallizes in $FCC$ with an edge length of $400 \ pm$. If it contains $0.1 \%$ Schottky defects, calculate its approximate density $[AW \text{ of } Fe = 56 \ g/mol]$. (in $g/cm^3$)

The formula of nickel oxide with metal deficiency defect in its crystal is $Ni_{0.98}O$. The crystal contains $Ni^{2+}$ and $Ni^{3+}$ ions. The fraction of nickel existing as $Ni^{2+}$ ions in the crystal is

In an ionic crystal,$F$-centers are.....

Which of the following defects,if present,lowers the density of a crystal?

What is the percentage of $Fe^{3+}$ in $Fe_{0.95}O$?