Due to vacancy defects,the density of a solid substance .............

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

The flame colours of metal ions are due to

Which of the following is $NOT$ true for Schottky defect?

Alkali halides do not show dislocation defect because

Ionic solids,with Schottky defects,contain in their structure