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?

Answer 1

Metal P is Zn (zinc), Q is Sn (tin), R is Pb (lead) and S is Fe (iron).

We arrive to the following conclusion:

Metal P (zinc) is used to form a thin layer on metal S (iron). The process of thin coating of zinc layer on 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.