To calculate the formal charge of the nitrogen atom in HCN, we need to follow these steps:1. Determine the number of valence electrons for nitrogen. Nitrogen is in group 15, so it has 5 valence electrons.2. Calculate the number of non-bonding lone pair electrons on nitrogen. In HCN, nitrogen has no lone pairs.3. Calculate the number of bonding electrons. Nitrogen forms a triple bond with carbon in HCN, which means it shares 6 electrons 3 pairs in the bond.4. Divide the number of bonding electrons by 2. This is because each bond consists of 2 electrons. In this case, 6 bonding electrons / 2 = 3.5. Subtract the number of non-bonding electrons and half the number of bonding electrons from the total number of valence electrons. In this case, the formal charge of nitrogen is 5 valence electrons - 0 non-bonding electrons - 3 half of bonding electrons = 2.So, the formal charge of the nitrogen atom in HCN is +2.