the salt is neutral in charge. OS of Ca is +2, so (NO3)2 bears -2 charges, so NO3 bears -1 charge, we know O holds -2 charge Thus, (the charge of N) + -2x3 =-1 so, N = +5 Ca +2, N +5, O -2 Solution the salt is neutral in charge. OS of Ca is +2, so (NO3)2 bears -2 charges, so NO3 bears -1 charge, we know O holds -2 charge Thus, (the charge of N) + -2x3 =-1 so, N = +5 Ca +2, N +5, O -2.