Materials may be classified according to their chemical structures. Four standard types of structure are metallic, ionic, simple molecular and giant molecular. The table lists some physical properties of four substances. Which of the substances has a simple molecular structure?
- Amelting point $64\,^{\circ}\text{C}$; reacts with water; electrical conductivity good when solid
- Bmelting point $113\,^{\circ}\text{C}$; insoluble; electrical conductivity always poor
- Cmelting point $767\,^{\circ}\text{C}$; soluble; electrical conductivity good when solid
- Dmelting point $1600\,^{\circ}\text{C}$; insoluble; electrical conductivity always poor