Read the passage and answer any four questions from (a) to (e).
During extraction of metals, electrolytic refining is used to obtain pure metals. During the process, the impure metal is made the anode and a thin strip of pure metal is made the cathode. The solution of the metal salt is used as an electrolyte. On passing the current through the electrolyte, the pure metal from the anode dissolves from the electrolyte. An equivalent of pure metal from the electrolyte is deposited on the cathode.
(a) The process of purification of the metal obtained after reduction, is called:
(i) Extraction
(ii) Refining
(iii) Froth floatation
(iv) Electrolysis
Answer
Refining is the process of purification of metal after reduction.
The correct answer is (ii)
(b) Which of the metals are refined by electrolytic refining?
(i) Au
(ii) Cu
(iii) Na
(iv) K
- I and II
- I and III
- II and III
- II and IV
Answer
In electrolytic refining, electric current is used to purify metals.
Metals like Cu, Ag, Zn, Au are refined by this method.
Na, K, and Ca cannot be refined using electrolysis because they are highly reactive. They are refined by electrolytic reduction instead.
So, the correct option is (a) I and II
(c) During electrolytic refining of zinc, it gets
(i) deposited on cathode.
(ii) deposited on anode.
(iii) deposited on cathode as well as anode.
(iv) remains in the solution.
Answer
Ions of zinc are positively charged , thus while electrolytic refining of zinc, zinc is deposited at the cathode (negatively charged pole) .
So, the correct answer is (I)
(d) In electrolytic refining of copper, impure copper act as __________and pure copper as __________:
(i) cathode, anode
(ii) cathode, electrolyte
(iii) anode, cathode
(iv) electrolyte, cathode
Answer
In electrolytic refining of any metal,
- The impure metal is placed at the anode
- The pure metal electrode at the cathode.
So, the correct answer is (iii)
(e) Anode is _______electrode while cathode is __________electrode:
(i) negative, positive
(ii) reducing, oxidising
(iii) both a and b
(iv) neither a nor b
Answer
- Anode is the negative electrode.
- The anode oxidises the metal in its oxide form.
- Cathode is a positive electrode.
- It reduces the metal to its pure form.
So, the correct option is (i)
