The set having incorrect statements is 1 . the Hall-Heroult process is used for the production of aluminium and iron 2 . pig iron is obtained from cast iron 3 . the blistered appearance of copper during the metallurgical process is due to the evolution of C O 2 4 . leaching of bauxite using concentrated NaOH solution gives sodium aluminate and sodium silicate

Step-by-step solution

Here only statement 4 is correct while rest are incorrect as Hall-Heroult process is used for production of only aluminium. Cast iron is obtained from pig iron P i g i r o n 4 % → b l a s t o f a i r c a s t i ro n 3 % The blistered appearance of copper during the metallurgical process is due to the evoluation of S O 2 . C u 2 S + 2 C u 2 O → 6 C u + S O 2 During leaching when bauxite is treated with concentrated NaOH, then sodium aluminate and sodium silicate is formed in the soluble form, whereas F e 2 O 3 is pre