Which of the following is an example of a covalent crystal solid?

Which of the following dopants is used in germanium to form $n-$type semiconductor?

For amorphous solids,select the correct option using $T$ (True) or $F$ (False) for the following statements:
$(1)$ They soften over a range of temperature.
$(2)$ Their physical properties like electrical conductivity and thermal conductivity are the same in all directions.
$(3)$ The arrangement of their particles is disordered.
$(4)$ They are hard and are less affected by pressure.

Explain $n$-type and $p$-type semiconductors.

Which of the following is a non-crystalline solid?

How many of the following compounds show ferrimagnetism?
$Fe_3O_4; MgFe_2O_4; NiFe_2O_4; MnO; CrO_2$