Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and hs high melting point?

• metallic bonding

• van der Waal's bonding

• Ionic bonding

• covalent bonding

A.

metallic bonding

Metallic bonding is formed due to the attraction of valence (free) electrons with the positive ion cores. Their conductivity decreases with rising of temperature. When visible light falls on a metallic crystal, the electrons of atoms absorb visible light, so they are opaque to visible light. However, some orbital electrons absorb energy and reach to an excited state. They then return to their normal state, remitting light of the same frequency.