A substance has a melting point of 8040C, is insoluble in water and is a good insulator of electricity. The substance is most likely
a) An ionic solid
b) A covalent network solid
c) A polar covalent solid
d) A nonpolar covalent solid
e) A metallic crystal
b) A covalent network solid
To determine the type of substance based on the given information, we can analyze the properties mentioned.
1) Melting point of 8040C: An extremely high melting point suggests strong bonds between the atoms or particles in the substance.
2) Insoluble in water: This indicates that the substance does not dissolve in a polar solvent like water. Substances that do not dissolve in water are typically nonpolar.
3) Good insulator of electricity: A substance that is a good insulator of electricity does not conduct electricity well. Insulators commonly have tightly bound electrons and a lack of free electrons.
Based on these properties, we can deduce that the substance is most likely a covalent network solid (option b). Covalent network solids are compounds made up of covalent bonds that form extended networks of covalently bonded atoms, typically with strong intermolecular forces. These compounds typically have high melting points, do not dissolve in water, and are poor conductors of electricity due to their lack of free electrons.
In contrast, ionic solids (option a) have high melting points, are often soluble in water, and conduct electricity when dissolved or molten. Polar covalent solids (option c) have lower melting points, are usually soluble in polar solvents, and may exhibit some conductivity. Nonpolar covalent solids (option d) have lower melting points, are generally insoluble in water, and do not conduct electricity. Metallic crystals (option e) have variable melting points, are generally insoluble in water, and are excellent conductors of electricity due to their free electrons.
Based on the given information, we can narrow down the options.
Insolubility in water suggests that the substance does not readily dissolve in water molecules, which indicates that it is not ionic or polar covalent.
A good insulator of electricity suggests that the substance does not allow the flow of electric charges easily, indicating that it is not metallic in nature.
Therefore, the most likely option is b) A covalent network solid. Covalent network solids have high melting points, are insoluble in water, and are good insulators of electricity.