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Question
Four metals P, Q, R and S are all obtained by the reduction of their oxides with carbon. Metal P is used to form a thin layer over the sheets of metal S to prevent its corrosion. Metal Q is used for electroplating tiffin boxes made of metal S whereas metal R is used in making car batteries. Metals Q and R form an alloy called solder. What are metals P, Q, R and S? How have you arrived at this conclusion?
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Solution
Metal P is Zn (zinc), Q is Sn (tin), R is Pb (lead), and S is Fe (iron). We arrive at the following conclusion:
Metal P (zinc) is used to form a thin layer on metal S (iron). The process of applying a thin zinc coating to iron objects is called galvanisation. This thin coating of zinc layer on iron objects protects it from corrosion (zinc is a highly reactive metal. It does not rust even in moisture because it forms a thin coat of zinc oxide on reacting with air).
Metal Q (tin) is used for electroplating tiffin boxes made of metal S (iron). This tin coating prevents the corrosion of iron. However, tin coating provides only outside protection.
Metal R (lead) is used in making car batteries. Metal Q (tin) and metal R (lead) are combined together to form an alloy called solder.
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