Answer:-

a. In Biology:

• Coordination compounds play essential roles in various biological processes.
• Chlorophyll, found in plants, is a complex of magnesium (Mg).
• Hemoglobin, present in blood, is a complex of iron (Fe).

b. In Medicines: i. Cisplatin, a platinum complex, is used in cancer treatment. ii. EDTA is employed for the treatment of lead poisoning.

c. To Estimate Hardness of Water:

• EDTA forms stable complexes with calcium ions (Ca²⁺) and magnesium ions (Mg²⁺), making it useful for determining water hardness.

d. In Electroplating:

• Coordination complexes are used in electroplating to control the supply of metal ions.
• Certain cyanide complexes, like K[Ag(CN)₂] and K[Au(CN)₂], are used for electroplating noble metals like silver (Ag) and gold (Au).

These examples illustrate the diverse and practical applications of coordination compounds in various fields, ranging from biology and medicine to analytical chemistry and materials science. Coordination chemistry continues to be a critical area of study and innovation with real-world implications.