Why do solids have a definite volume?

Classify the following as amorphous or crystalline solids. Polyurethane, Naphthalene, Benzoic acid, Teflon, Potassium nitrate, Cellophane, Polyvinyl chloride, Fiber glass, Copper.

What type of stoichiometric defect is shown by ZnS.

Ionic solids conduct electricity in molten state but not in solid state. Explain.

Distinguish between : Face - centred and body - centred unit cells.

What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

What is the total number of atoms per unit cell in a face - centered cubic structure (fcc)?

Name an element with which silicon can be doped to give an n-type semi conductor.

Which point effect in crystal doesn't alter the density of the relevant solid?

Define the term amorphous.

Define void.

What is point defect in crystals?

Diamond and solid rhombic sulphur are covalent solids but the latter has very low melting point than the former. Explain why?

Aluminium crystallises in a fee structure. Atomic radius of the metal is 125 pm. What is the length of the side of the unit cell of the metal?

Define the term: space lattice.