Look at the data in the table below showing the physical properties of three substances, X, Y, and Z.
| Substance | Melting point (∘ ^\circ\,∘C) | Boiling point (∘ ^\circ\,∘C) | Electrical conductivity | Density (g/cm3^33) |
|---|---|---|---|---|
| X | -115 | -78 | Does not conduct | 0.0016 |
| Y | 1455 | 2913 | Good conductor in solid and liquid states | 8.90 |
| Z | 772 | 1935 | Does not conduct as a solid, but conducts when molten or dissolved in water | 2.15 |
What is the type of bonding present in each of the substances X, Y, and Z? Explain how you can tell from the data.