Which of the following metallic oxides is antiferromagnetic?

Which of the following oxides shows electrical properties like metals?

$STATEMENT-1$: Band gap in germanium is small.
$STATEMENT-2$: The energy spread of each germanium atomic energy level is infinitesimally small.

Why are liquids and gases called fluids while solids are rigid?

Solid $A$ is a very hard electrical insulator in solid as well as in molten state and melts at extremely high temperature. What type of solid is it?

Under which situations can an amorphous substance change to crystalline form?