The melting point of element X is 686 degree C. X is a good conductor of electricity in it's solid & molten states. Deduce the bonding & ...
structure of X & explain how they account for these properties.
Because of its high melting point and ability to conduct electricity element X must be a metal. Metals have what is called "metallic bonding" in which the outer electrons are held loosely to the nucleus and are free to move. This bonding is what give metals the property of conductivity - both for heat and electricity. This particular bond structure also allows metals to be shaped into wires (ductility) and shaped into thin sheets (malleable)
Because this element is a good conductor of electricity, and has a high melting point it is quite likely a metal. Non-metals tend to be poor conductors of electricity, and have lower melting points than metals.
Now that we know that this element is a metal we know that the bonds it will form will be ionic (bond between a metal and a non-metal). In ionic bonding electrons are transferred rather than shared. The transferring of electrons causes an electrostatic attraction between the two elements causing them to come to gather.
Also because the bond is ionic we know that the bond it forms will likely be crystalline.