With which one of the following elements should silicon be doped to give a $p-$type semiconductor?

What is a domain in the context of magnetism in solids?

Which of the following is an example of a network solid?

Give examples of crystalline solids and polycrystalline solids.

Assertion : On heating ferromagnetic or ferrimagnetic substances,they become paramagnetic.
Reason : The electrons change their spin on heating.

Which among the following is ferromagnetic in nature?