The formal charge on the nitrogen atom in the compound NH4+ can be calculated using the following formula:Formal charge = Valence electrons of the atom - Non-bonding electrons - 1/2 Bonding electrons For nitrogen in NH4+, the number of valence electrons is 5 as nitrogen is in group 15 of the periodic table . There are no non-bonding electrons on the nitrogen atom in this compound, as all of its electrons are involved in bonding with the four hydrogen atoms. Each nitrogen-hydrogen bond has 2 electrons, so there are a total of 8 bonding electrons.Now, we can calculate the formal charge:Formal charge = 5 - 0 - 1/2 8 = 5 - 4 = +1So, the formal charge on the nitrogen atom in the compound NH4+ is +1.