How many valence electrons are transferred from nitrogen atom to potassium in the formation of the compound potassium nitride?

            3 electrons are gained by one nitrogen atom in the formation of K₃N.

Explanation:

The reaction is as follow,

                                       6 K + N₂    →    2 K₃N

Oxidation of K,

                                       K     →     K⁺  +  1 e⁻
Or,
                                    6 K     →    6 K⁺  +  6 e⁻

In oxidation reaction potassium atom transfers one electron per atomn and six electrons per six atoms.

Reduction of N;
                                  N₂  +  6 e⁻    →    2 N³⁻

In reduction reaction one molecule of N₂ gains six electrons and 3 electrons per one atom

1.from liquid state to gaseous state is evaporation 3.solid to liquid is melting 5. solid to gaseous state is sublimation 6. gas to solid state is decomposition 7. a change of state is known as the states of matters