Answer :
Final answer:
An ionic crystal typically has a high melting point due to the strong forces between cations and anions, with d) 600 degrees Celsius being a more representative value than the minimum stated criteria of 400 °C. So the correct option is d.
Explanation:
The expected melting point for an ionic crystal, based on the statement that a high melting point is at least 400 degrees Celsius, would be d) 600 degrees Celsius. Ionic crystals have strong attractive forces between cations and anions which contribute to a very strong crystal lattice. This results in the requirement of a significant amount of energy to break all the ionic bonds during the melting process. For example, sodium chloride, an ionic compound, has a melting point of about 800 °C, much higher than the minimum given for a high melting point. Therefore, while options a) and b) are too low for an ionic crystal's high melting point, option c) meets the minimal criterion; however, the typical melting point for many ionic crystals is usually even higher, making option d) more representative of the expected value.
