A solid with higher melting and boiling points is likely to be?

Analyze the question: We are asked which type of solid typically has high melting and boiling points. This depends on the type of bonding and the forces holding the particles together.

Explain the concept:

• Electrovalent (ionic) compounds are made of positive and negative ions arranged in a giant crystal lattice. The electrostatic attraction between the oppositely charged ions is very strong, so a large amount of energy is needed to break it. This gives them high melting and boiling points (e.g., NaCl melts at about 801°C).
• Covalent compounds (simple molecular ones) consist of discrete molecules held together by weak intermolecular forces (van der Waals forces). Little energy is needed to separate the molecules, so they usually have low melting and boiling points (e.g., sugar, wax, CO₂).
• Dative (coordinate covalent) compounds behave much like covalent compounds, so they generally have low melting and boiling points.
• Non-metals are mostly simple molecular substances (O₂, S₈, P₄) with low melting points. Giant covalent structures like diamond and graphite are exceptions, but non-metals as a group are not characterized by high melting points.

Solution:

1. Identify the property: high melting and boiling points mean strong forces between particles.
2. The strongest such forces among the options are the ionic bonds in a crystal lattice.
3. Ionic bonding is also called electrovalent bonding.

Answer: Option C, an electrovalent compound.

Exam tip: Remember the pattern "Ionic = High, Covalent = Low." Ionic solids are hard, brittle, have high melting points, and conduct electricity when molten or dissolved in water. Simple covalent compounds are the opposite: low melting points and poor conductivity.