Which of the following is a pseudo solid?

What is the main use of $Quartz$?

Classify the following as amorphous or crystalline solids: Polyurethane,naphthalene,benzoic acid,teflon,potassium nitrate,cellophane,polyvinyl chloride,fibre glass,copper.

When mechanical stress is applied to a crystal,a small amount of electricity is produced. This property is called ........

Assertion : Stability of a crystal is reflected in the magnitude of its melting point.
Reason : The stability of a crystal depends upon the strength of the interparticle attractive force.

Which of the following is not a property of solids?