Which of the following is isotropic?

Classify the following materials into superconductors,conductors,semiconductors,and insulators: $Cu$,$Al$,$Si$,$Ge$,glass,Teflon,$Au$,$Pt$,$CuO$ (at low temperature),graphite,carbon black,and alloys at low temperature.

What type of information is collected using scanning electron microscopy $(SEM)$?

Crystalline solids possess $......$.

The characteristic features of solids are

Ionic solids are poor conductors of electricity because .......