Answer :Solid in bottle a is ionic, solid in bottle b is molecular and solid in bottle c is ionic.
Explanation :
Ionic compound is formed when a metal atom donates one or more electrons to a non metal. This results in the formation of a cation ( a positive ion) and an anion ( a negative ion). These ions are bonded to each other by electrostatic attraction.
The intermolecular forces in case of a an ionic compound are very strong.
The melting point of a substance depends on how strongly the molecules are attracted to each other. Stronger the forces, higher is the melting point.
Therefore ionic compounds always have very high melting points.
On the other hand, covalent compounds have weak intermolecular forces. Therefore they have low melting points.
Based on above discussion, we can classify the given compounds as follows.
a) Solid in bottle a is Ionic as it has high melting point.
b) Solid in bottle b is molecular as it has low melting point.
c) Solid in bottle c is Ionic as it has high melting point.