The data in the table describes the properties of three substances. based on the data, identify whether each substance is ionic, polar covalent, or non-polar covalent.

Substance A is ionic because in molten and aqueous solution conduct electricity and dissolves in water. This is because it dissociate in ions and ion conduct electicity and dissolve in polar molecules (water). Ionic bond is very strong (high melting point).
Substance B non polar covalent, because it is not dissolve in polar molecules and has weak intermolecular forces (low melting point).
Substance C is polar covalent because polar molecules have stronger intermolecular forces than non-polar and higher melting points.

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.