Gold, silver, platinum, and copper are found in the free state. Copper and silver are also found in the combined state as sulphide or oxide ores.

Metals at the top of the activity series are highly reactive and are never found in nature as free elements. Moderately reactive metals (Zn, Fe, Pb, etc.) are found mainly as oxides, sulphides, or carbonates in the earth’s crust.

Moderately reactive metals in the middle of the activity series include iron, zinc, lead, and copper. They are typically present as sulphides or carbonates in nature.

Metal sulphides are converted into oxides through roasting, which involves strong heating in the presence of excess air. Carbonate ores are changed into oxides through calcination, achieved by strong heating in limited air.

Detergents are commonly used in shampoos and cleaning products for clothes. Unlike soaps, detergents remain effective in hard water due to their chemical structure, eliminating the issues of scum formation and difficulty in foam production.