Answer: Sulphur Sulphur is a non metal while all the others are metals.
Answer: Boron Boron is a metalloid while all the others are non-metals.
Answer: Brass Brass is an alloy while all the others are metals.
Answer: Phosphorous Phosphorous is an element while all the others are alloys.
Answer: Froth floatation Froth floatation is a process used for concentration of the ores while all the others are methods of preventing corrosion.
Answer: Calcination Calcination is a process used for concentration of the bauxite ore while all the others are methods of preventing corrosion.
Answer: Cu Cu is a transition element while all the others are normal elements. OR Cu belongs to the d-block while all the others belong to the s-block.