Draw the Lewis structure for the HCN molecule. Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all lone pairs of electrons.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.