Predict Which among the following substances is likely to have a relatively high melting point.(more than one answer may be selected)

* P4
* CaCl2
* CCl4
* AlN
* CaC2
* None of the above

CaCl2, AIN, and CaC2

Among the given substances, the following are likely to have a relatively high melting point:

- CaCl2 (Calcium chloride)
- AlN (Aluminum nitride)

Both CaCl2 and AlN have strong ionic bonds, which typically result in high melting points. These bonds require more energy to break, resulting in a higher temperature needed for melting.

To predict which substance is likely to have a relatively high melting point, we need to consider the types of chemical bonds present in each substance.

1. P4 (Phosphorus): P4 consists of covalent bonds. Covalent compounds generally have lower melting points since the intermolecular forces holding the molecules together are relatively weak. Therefore, P4 is unlikely to have a high melting point.

2. CaCl2 (Calcium chloride): CaCl2 is an ionic compound. Ionic compounds tend to have higher melting points because the electrostatic forces between positively and negatively charged ions are stronger. Therefore, CaCl2 is likely to have a relatively high melting point.

3. CCl4 (Carbon tetrachloride): CCl4 is a covalent compound. Similar to P4, covalent compounds have lower melting points. Hence, CCl4 is unlikely to have a high melting point.

4. AlN (Aluminum nitride): AlN is an ionic compound that contains both aluminum (Al) and nitrogen (N). Like CaCl2, ionic compounds generally have high melting points, so AlN is likely to have a relatively high melting point.

5. CaC2 (Calcium carbide): CaC2 is an ionic compound. Again, similar to other ionic compounds, CaC2 is expected to have a high melting point.

Based on the analysis above, both CaCl2 and AlN are likely to have relatively high melting points. Therefore, the correct answers are CaCl2 and AlN.

Most ionic compounds have high melting points; most covalent compounds have low melting points. That isn't a hard and fast rule (diamond, for example,doesn't follow this rule).

I see three compounds in your list with more than a little ionic character.