Write observed electronic configuration of chromium (Z = 24).(ii) Calculate magnetic moment of Ti3+ by using spin only formula. (Z of Ti = 22)(iii) Define Green chemistry.

Answer: (i) [Ar] 3d⁵ 4s¹ (ii) 1.73 B.M. (iii) Definition below.

(i) Cr (Z = 24): 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹. The expected 3d⁴4s² is not observed because the exactly half-filled 3d⁵ subshell (with 4s¹) has extra stability.

(ii) Ti: [Ar]3d²4s²; Ti³⁺: [Ar]3d¹, so the number of unpaired electrons \(n = 1\).

(iii) Green chemistry: Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances, so as to protect human health and the environment (with less waste, safer chemicals and less energy).