Magnetic moment of A+3 ion is 5.48 × 10–23 J/T (and 9.27 × 10–24 = 1BM). If A belongs to 4th period, then element A is

Magnetic momen of Given 1 BM = 9.27 × 10-24 J/TMagnetic moment of = 5.9 BM              n = 5Number of unpaired electrons in A+3 ion = 5Since it belongs to 4th period and having 5 unpaired electrons it must be a 3d -series elementThus A+3 = [Ar]3d5then A(z = 26) = [Ar]4s23d6Element 'A' is Iron (Fe)