The table lists properties of four substances at room temperature. substance state conducts electricity A solid yes (when molten) B gas no C solid yes D sol...
Question 1 Report
The table lists properties of four substances at room temperature.
| substance | state | conducts electricity |
| A | solid | yes (when molten) |
| B | gas | no |
| C | solid | yes |
| D | solid | no, very high melting point |
Which substance is a simple molecular covalent compound?
Answer Details
Use the state and the conductivity together to identify each structure. A simple molecular covalent compound has weak forces between its molecules, so it melts and boils at low temperatures and is often a gas at room temperature, and it contains no ions or free electrons, so it never conducts electricity.
The substance labelled B is the only one that is a gas and does not conduct, so it is the simple molecular covalent compound.
The substance that is solid and conducts only when molten is ionic: its ions become free to move once the lattice breaks down. The solid that conducts while still solid has delocalised electrons, so it is a metal. The solid that does not conduct but has a very high melting point is giant covalent, like silicon(IV) oxide.
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