Which of the following exists as covalent crystals in the solid state?

Which of the following metals expands on solidification?

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

Which of the following possesses a layered crystal structure?

Select the correct statements.
$(A)$ Crystalline solids have long range order.
$(B)$ Crystalline solids are isotropic.
$(C)$ Amorphous solids are sometimes called pseudo solids.
$(D)$ Amorphous solids soften over a range of temperature.
$(E)$ Amorphous solids have a definite heat of fusion.
Choose the most appropriate answer from the options given below:

Which from the following dopants is used in germanium to produce $p-$type semiconductor?