CBSE Class 12 Chemistry Purification Of Metals Worksheet

CBSE Class 12 Chemistry Purification of Metals. CBSE issues sample papers every year for students for class 12 board exams. Students should solve the CBSE issued sample papers to understand the pattern of the question paper which will come in class 12 board exams this year. The sample papers have been provided with marking scheme. It’s always recommended to practice as many CBSE sample papers as possible before the board examinations. Sample papers should be always practiced in examination condition at home or school and the student should show the answers to teachers for checking or compare with the answers provided. Students can download the sample papers in pdf format free and score better marks in examinations. Refer to other links too for latest sample papers. 

CONCEPTS COVERED:

• Process of refining
• Reactions utilized in various processes
• Identification of reagents used in various processes

Question. Match the column:
Column A
1. Zone refining
2. Van Arkel method
3. Electrolytic process
4. Liquation
5. Distillation

Column B
(A) Zirconium, Titanium
(B) Aluminium
(C) Gallium
(D) Zinc
(E) Tin

Answer: 1 - (C), 2 - (A), 3 - (B), 4 - (E), 5 - (D)

Question. Which of the following reaction involves during Mond’s process?
(a) \( \text{Ni} + 4\text{CO} \rightarrow \text{Ni(CO)}_4 \)
(b) \( \text{Ni(CO)}_4 \rightarrow \text{Ni} + 4\text{CO} \)
(c) Both a & b
(d) \( \text{Zr} + 2\text{I}_2 \rightarrow \text{ZrI}_4 \)

Answer: (c) Both a & b

Question. Which of the expression is related with electrochemical principle?
(a) \( \Delta G^0 = -RT\ln K^0 \)
(b) \( \Delta G^0 = -nFE^0 \)
(c) \( \Delta G^0 = \Delta H^0 - T\Delta S \)
(d) None of the options

Answer: (b) \( \Delta G^0 = -nFE^0 \)

Question. During refining by electrolysis, impure copper is taken as
(a) Cathode
(b) Anode
(c) Both a and b
(d) None of the options

Answer: (b) Anode

Question. Chromatography purification is based on the principle of
(a) Chemical kinetics
(b) Electrochemistry
(c) Adsorption
(d) Absorption

Answer: (c) Adsorption

Question. Pure metals get deposited at which electrode
(a) Cathode
(b) Anode
(c) Both a and b
(d) None of the options

Answer: (a) Cathode

Question. Give one example of a metal purified by zone refining.

Answer: Gallium (Ga)

Question. Give one example of a metal purified by vapour phase refining.

Answer: Titanium

Question. Give one example of a metal purified by electrolysis.

Answer: Silver

Question. Give one example of a metal purified by liquation.

Answer: Tin (Sn)

Question. Give one example of a metal purified by distillation.

Answer: Zinc (Zn)

Question. During froth floatation process, the froth is stabilized using ________________.

Answer: cresol

Question. For an ore containing PbS and ZnS, ________________is used as a depressant.

Answer: NaCN

Question. The sulphide ore is made more hydrophobic using collectors like _________.

Answer: pine oil

Question. During the extraction of copper having iron as impurity, the slag formed is _________.

Answer: \( \text{FeSiO}_3 \)

Question. Apart from cryolite, _________can be used in the metallurgy of aluminium.

Answer: \( \text{CaF}_2 \)

Question. Identify the process: \( 2\text{Al}_2\text{O}_3 + 3\text{C} \rightarrow 4\text{Al} + 3\text{CO}_2 \)

Answer: Hall-Heroult process

Question. Identify the process: \( \text{ZrI}_4 \rightarrow \text{Zr} + 2\text{I}_2 \)

Answer: Van Arkel method

Question. Identify the process: \( \text{CaO} + \text{SiO}_2 \rightarrow \text{CaSiO}_3 \)

Answer: Extraction of iron (formation of slag)

Question. Identify the process: \( \text{ZnCO}_3 \rightarrow \text{ZnO} + \text{CO}_2 \)

Answer: Calcination

Question. Identify the process: \( \text{ZnS} + 3\text{O}_2 \rightarrow 2\text{ZnO} + 2\text{SO}_2 \)

Answer: Roasting

Question. Match the ore with the processes involved during the extraction of the metal:
Ores: bauxite, zinc blende, haematite, copper pyrite, zinc carbonate.
Processes: reduction with coke, leaching, reduction in a blast furnace, roasting of sulphide ore, electrochemical reduction, reduction in a reverberatory furnace.

Answer:
1. Bauxite: Leaching and electrochemical reduction
2. Zinc blende: Roasting of sulphide ore and reduction with coke
3. Haematite: Reduction in blast furnace
4. Copper pyrite: Roasting of sulphide ore and reduction in a reverberatory furnace
5. Zinc carbonate: Reduction with coke

Question. Complete the analogy: \( \text{Al}_2\text{O}_3 : \text{NaOH} :: \text{Ag}_2\text{S} : \text{____} \)

Answer: NaCN

Question. Complete the analogy: \( \text{FeO} : \text{SiO}_2 :: \text{SiO}_2 : \text{____} \)

Answer: CaO

Question. Complete the analogy: Aluminium : bauxite :: silver : ______

Answer: silver glance

Question. Complete the analogy: \( \text{Ni} : \text{Ni(CO)}_4 :: \text{Zr} : \text{____} \)

Answer: \( \text{ZrI}_4 \)

Question. Complete the analogy: \( \text{Na[Al(OH)}_4\text{]} : \text{CO}_2 :: \text{[Au(CN)}_2\text{]}^- : \text{____} \)

Answer: Zn