Answer:
Substance A is a Giant covalent structure with covalent bonding
Step-by-step explanation:
Substance A is a Giant covalent structure. There are strong covalent bonds between the atoms and a large amount of heat energy is needed to break the bonds resulting in high melting point. Substance A does not conduct electricity in molten state reason being, it exist as molecules which are electrically neutral and there are no mobile charged carriers.
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