Amorphous solids are......

The value of the heat of fusion of $NaCl$ is:

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:

Which of the following is not true about the amorphous solids?

Explain:
$(i)$ The basis of similarities and differences between metallic and ionic crystals.
$(ii)$ Why are ionic solids hard and brittle?

Which of the following statements is true for a crystalline solid?