The following question consists of five figures marked A, B, C, D and E called the Problem Figures followed by five other figures marked 1, 2, 3, 4 and 5 called the Answer Figures. Select a figure from amongst the Answer Figures which will continue the same series as established by the five Problem Figures.Problem Figures: Answer Figures:
(A) (B) (C) (D) (E) (1) (2) (3) (4) (5)
The symbols move in the sequence in the first step. In each subsequent step, the symbols move in the sequence obtained by rotating the previous sequence through 90oACW. Also in each step, the symbol that reaches the encircled position gets replaced by a new one.
Ans: Removal of impurities from an impure metal is called refining.
The electrolytic refining of copper is done in an apparatus shown below
The block of impure copper is made as anode. The cathode is made of a thin plate of pure copper. The electrolyte is a solution of copper sulphate, containing a small amount of dilute sulphuric acid. On passing electric current, copper dissolves from the anode into the electrolyte. An equivalent amount of copper from the electrolyte is then deposited on the cathode. Crude copper contains very small amounts of iron, silver and gold. The more reactive metals, such as iron, dissolve in the solution and remain there. The less reactive metals, such as silver and gold, fall below the anode in the electrolytic cell as anode mud. These metals are recovered in the native state.