Which of the following is an amorphous solid?

Explain Ferrimagnetism.

$A$ pure crystalline substance,on being heated gradually,first forms a turbid-looking liquid and then the turbidity completely disappears. This behaviour is the characteristic of substances forming

Explain:
$(i)$ The basis of similarities and differences between metallic and ionic crystals.
$(ii)$ Why are ionic solids hard and brittle?

Which of the following components of cement sets at the slowest rate?

What is a semiconductor? Describe the two main types of semiconductors and contrast their conduction mechanism.