Determine the mass of copper 2 trioxonitrate 5 that would be formed when 15g of copper is added to excess dilute trioxonitrate 5 acid, (cu=63,N=14,O=16)

Cu in dilute HNO3 forms

3Cu+8HNO3​​⟶3Cu(NO3​)2​​+4H2​O+2NO
15g Cu = 0.236 moles
the equation tells you that you will get that many moles of Copper Nitrate
so, 0.236mol * 187.56g/mol = 44.4g

trioxonitrate 5 acid. Correct IUPAC name is nitric acid.

copper 2 trioxonitrate 5. Correct IUPAC name is copper(II) nitrate.