Final answer:
Covalent compounds generally have lower melting and boiling points and variable water solubility but are often soluble in organic solvents like ethanol, which is option (D) from the question.
Step-by-step explanation:
The properties of covalent compounds are distinct from those of ionic compounds. Covalent compounds typically have lower melting and boiling points because the intermolecular forces between the molecules are not as strong as the ionic bonds in crystalline structures. Consequently, covalent compounds do not require as much energy to disrupt these forces. When it comes to solubility, covalent compounds are of variable solubility in water. However, many covalent compounds are soluble in organic solvents like ethanol due to similarities in polarity and intermolecular forces.
Regarding the options provided in the question:
- A high melting point and high boiling point (A) is generally characteristic of ionic, not covalent compounds.
- Capacity for conducting electricity when molten or dissolved in water (B) also pertains to ionic compounds due to the mobility of ions.
- Being crystalline solid white at room temperature (C) can occur in some covalent compounds, but it is not a defining character.
- Being soluble in organic solvents such as ethanol (D) is more common among covalent compounds, making this the most correct choice provided.