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 ?

Explanation

Since , the solid 'A' is an insulator in solid as well as in molten state , it shows the absence of ions in it . Moreover it melts at extremely high temperature , so it is a giant molecule . These are the properties of covalent solids . So , it is a covalent solid .