Becoming liquefied by heat
If the name of a compound contains the name of a metal and a nonmetal, the compound is probably an ionic compound. Ionic compounds typically form when metals donate electrons to nonmetals, resulting in the formation of positive and negative ions. This type of compound often has a high melting point and conducts electricity when dissolved in water. Examples include sodium chloride (NaCl) and magnesium oxide (MgO).
No, diamonds cannot be liquefied. Diamonds are the hardest naturally occurring substance and have a very high melting point of around 3,550 degrees Celsius, which is much higher than any typical method of liquefaction.
The solid is most likely a metal. Metals have high melting points, are relatively soft (compared to nonmetals), and conduct both electricity and heat well due to the presence of free electrons in their structure.
During recrystallization, impurities are removed as the compound is dissolved and then slowly cooled to allow for the formation of pure crystals. As a result, the melting point of the compound should increase after recrystallization because the presence of impurities lowers the melting point of the compound.
metaloid
It has a very high melting point, whereas most molecular substances have lower melting points. When it dissolves in water, the sodium and chloride ions dissociate and the resulting salt water conducts electricity.
It's likely but not definitive. Giant covalent substances like diamond also have high melting and boiling points. To be sure you would have to show that the melted or dissolved substance conducts electricity.
Becoming liquefied by heat
Sodium chloride fits this description. It has a melting point of 1074 K and conducts electricity when dissolved in water as it dissociates into sodium and chloride ions, but does not conduct electricity in the solid state because the ions are not free to move.
Molecular compounds generally do not conduct electricity and have low melting points.
They have high melting and boiling points and can conduct electricity when they are molten or a liquid.
Melting is when a solid becomes hot and "melts" into a liquid. (wax)
They are hard and brittle, conduct electricity in water, and have high melting and boiling points. (:
The types of crystalline solids that are usually good conductors of heat and electricity are those that have valence electrons. It is the valence electrons that are responsible for the conduction of heat and electricity.
Covalent compounds can not conduct electricity whether dissolved or not. There are not any mobile charges available to create a current. However the compound in this question is a gas, not sure which one. But a gas such as ammonia, when dissolving in water can react with the water to form an ion, in this case, Ammonium. The presence of dissolved ions will allow an electric current to flow.
Ionic compounds will have a high melting point and conduct electricity when melted or dissolved in water due to their ability to form charged ions that can carry electric current.