(a) Electron dot structure of ethyne (C₂H₂):
Ethyne has a triple bond between the two carbon atoms.
$$\text{H} : \text{C} ::: \text{C} : \text{H}$$
(Each carbon shares 3 pairs of electrons with the other carbon and 1 pair with hydrogen.)
(b) Two differences between covalent and ionic compounds:
| Property | Covalent Compounds | Ionic Compounds |
|---|---|---|
| Melting/Boiling Point | Generally low | Generally high |
| Solubility in water | Generally insoluble or slightly soluble | Generally soluble |
(Alternatively: Ionic compounds conduct electricity in solution; covalent compounds generally do not.)
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