Which one is an example of an amorphous solid?

The characteristic features of solids are

$A$ 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

Given below are two statements.
Statement $I$ : $O_2, Cu^{2+}$ and $Fe^{3+}$ are weakly attracted by magnetic field and are magnetized in the same direction as magnetic field.
Statement $II$ : $NaCl$ and $H_2O$ are weakly magnetized in opposite direction to magnetic field.
In the light of the above statements,choose the most appropriate answer from the options given below:

Write a note on covalent or network solids.

Which of the following is not a property of solids?