Question 4 - Case Based Questions (MCQ) - Chapter 3 Class 10 - Metals and Non-Metals

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  

1. I and II 
2. I and III  
3. II and III 
4. 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)