Final answer:
Among the given options, d)HCN (hydrogen cyanide) is the covalent electrolyte because it is a covalent compound that can produce ions when dissolved in water.
Step-by-step explanation:
The question asks about which compound among the given options is a covalent electrolyte. A covalent electrolyte is a compound that consists of covalent bonds and is able to conduct electricity when dissolved in water. Covalent electrolytes typically dissociate to a small extent, producing a low concentration of ions.
Examining the options:
- Na₂CO₃ (sodium carbonate) is an ionic compound consisting of Na+ and CO₃²- ions when dissolved in water.
- [Co(NH₃)₆]²+ (hexaamminecobalt(II) ion) is predominantly an ion and forms ionic bonds with counterions.
- MnO₂ (manganese dioxide) is primarily ionic with some covalent character due to the metal and oxygen bonding.
- HCN (hydrogen cyanide) is a compound with a covalent network that weakly ionizes in water to produce H+ and CN- ions, making it a covalent electrolyte.
Therefore, d)HCN is the correct answer; it is a covalent compound (as opposed to ionic) that acts as an electrolyte due to its ability to produce ions in solution.