Free Ncert Solutions for 11th Class Chemistry Organic Chemistry: Some Basic Principles & Techniques / कार्बनिक रसायन : कुछ मूलभूत सिद्धांत एवं तकन

1)

Which of the ores mentioned in Table 6.1 can be concentrated by magnetic separation method?

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2)

What is the significance of leaching in the extraction of aluminium?

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3)

The reaction, Cr2O3 + 2Al

Al2O3 + 2Cr (

G° = ?421 kJ) is thermodynamically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?

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4)

Is it true that under certain conditions, Mg can reduce SiO2 and Si can reduce MgO? What are those conditions?

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5)

Copper can be extracted by hydrometallurgy but not zinc. Explain.

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6)

What is the role of depreciation in froth floatation process?

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7)

Why is the extraction of copper from its pyrite difficult than that from its oxide through reduction?

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8)

Explain (i) zone refling (ii) column chromatography.

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9)

Out of C or CO, which is a better reducing agent at 673 K?

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10)

Name the common elements present in anode mud in the electro-refining of copper, which get collected as anode mud. Why are they so present?

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11)

Write the chemical reactions which take place in different zones in the blast furnace during the extraction of iron.

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12)

Write the chemical reactions taking place in the extraction of zinc from zinc blende.

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13)

State the role of silica in the metallurgy of copper.

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14)

What is meant by the term chromatography?

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15)

What criterion is followed for the selection of the stationary phase in chromatography?

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16)

Describe a method for the refining of nickel.

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17)

How can you separate alumina from silica in a bauxite ore associated with silica? Give equations if any.

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18)

Giving examples differentiate between calcinations and roasting.

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19)

How is 'cast iron' different from 'pig iron'?

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20)

Differentiate between minerals and ores.

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21)

Why is copper matte put in silica lined converter?

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22)

What is the role of cryolite in the metallurgy of aluminium?

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23)

How is leaching carried out in case of low grade copper?

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24)

Why is zinc not extracted from zinc oxide through reduction using CO?

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25)

How much of

for the formation of Cr2O3 is ?540 kJ mol?1 and that of Al2O3 is ?827 kJ mol?1 Is the reduction The value of Cr2O3 possible with Al ?

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26)

Out of C and CO, which is a better reducing agent for ZnO?

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27)

The choice of a reducing agent in a particular case depends on the thermodynamic factors. How do you agree with this statement? Support your opinion with two examples.

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28)

Name the processes from which chlorine is obtained as the by- product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?

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29)

What is the role of graphite rod in the electrometallurgy of aluminium?

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30)

Outline the principles of refining of metals by following methods : (i) Zone refining (ii) Electrolytic refining (iii) Vapour phase refining.

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31)

Predict the conditions under which aluminium might be expected to reduce magnesium oxide.

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32) In the extraction of chlorine by electrolysis of brine............ (a) oxidation of ion to chlorine gas occurs (b) reduction of ion to chlorine gas occurs (C) for overall reaction has negative value (D) a displacement reaction takes place

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33) When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains (a) sulphides of copper (II) and iron (II) (b) sulphides of copper (11) and iron (111) (c) sulphides of copper (I) and iron (II) (d) sulphides of copper (I) and iron (III)

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34) Which of the following reactions is an example of autoreduction? (a) (b) (c) (d)

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35) A number of elements are available in earth's crust but most abundant elements are.............. (a) Al and Fe (b) Al and Cu (c) Fe and Cu (d) Cu and Ag

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36) Zone refining is based on the principle that.......... (a) impurities of low boiling metals can be separated by distillation. (b) impurities are more soluble in molten metal than in solid metal. (c) different components of a mixture are differently adsorbed on an adsorbent. (d) vapours of volatile compound can be decomposed in pure metal.

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37) In the extraction of copper from its sulphide ore, the metal is formed by the reduction of with (a) (b) CO (c) (d)

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38) Brine is electrolysed by using inert electrodes. The reaction at anode is......... (a) (b) (c) (d)

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39) In the metallurgy of aluminium............ (a) is oxidised to Al (s). (b) graphide anode is oxidised to carbon monoxide and carbon dioxide. (c) oxidation state of oxygen changes in the reaction at anode. (d) oxidation state of oxygen changes in the overall reaction involved in the process.

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40) Electrolytic refining is used to purify which of the following metals? (a) Cu and Zn (b) Ge and Si (c) Zr and Ti (d) Zn and Hg

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41) Extraction of gold and silver involves leaching the metal with ion. The metal is recovered by...... (a) displacement of metal by some other metal from the complex ion. (b) roasting of metal complex. (c) calcination followed by roasting. (d) thermal decomposition of metal complex.

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42) Choose the correct option of temperature at which carbon reduces to iron and produces CO. (a) Below temperature at point A (b) Approximately at the temperature corresponding to point A (c) Above temperature at point A but below temperature at point D (d) Above temperature at point A

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43) Below point 'A' can............. (a) be reduced by carbon monoxide only. (b) be reduced by both carbon monoxide and carbon. (c) be reduced by carbon only. (d) not be reduced by both carbon and carbon monoxide.

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44) For the reduction of at the temperature corresponding to point D, which of the following statements is correct? (a) AC value for the overall reduction reaction with carbon monoxide is zero. (b) AC value for the overall reduction reaction with a mixture of 1 mol carbon and 1 mol oxygen is positive. (c) AC value for the overall reduction reaction with a mixture of 2 mol carbon and 1 mol oxygen will be positive. (d) AC value for the overall reduction reaction with carbon monoxide is negative.

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45) At the temperature corresponding to which of the points in Fig. will be reduced to Fe by coupling the reaction with all of the following reactions? 1. 2 3. (a) Point A (b) Point B (c) Point D (d) Point £

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46) Which of the following options are correct? (a) Cast iron is obtained by remelting pig iron with scrap iron and coke using hot air blast. (b) In extraction of silver, silver is extracted as cationic complex. (c) Nickel is purified by zone refining. (d) Zr and Ti are purified by van Arkel method.

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47) In the extraction of aluminium by Hall - Heroult process, purified is mixed with to (a) lower the melting point of (b) increase the conductivity of molten mixture. (c) reduce into Al(5) (d) acts as catalyst

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48) Which of the following statements is correct about the role of substances added in the froth floatation process? (a) Collectors enhance the non-wettability of the mineral particles. (b) Collectors enhance the wettability of gangue particles. (c) By using depressants in the process two sulphide ores can be separated. (d) Froth stabilisers decrease wettability of gangue.

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49) In the froth floatation process, zinc sulphide and lead sulphide can be separated by............... (a) using collectors (b) adjusting the proportion of oil to water (c) using depressant (d) using froth stabilisers

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50) Common impurities present in bauxite are........ (a) (b) (c) (d)

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51) Which of the following ores are concentrated by froth floatation? (a) Haematite (b) Galena (c) Copper pyrites (d) Magnetite

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52) Which of the following reactions occur during calcination? (a) (b) (c) (d)

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53) For the metallurgical process of which of the ores calcined ore can be reduced by carbon? (a) Haematite (b) Calamine (c) Iron pyrites (d) Sphalerite

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54) The main reactions occurring in blast furnace during extraction of iron from haematite ore .......... (a) (b) (c) (d)

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55) In which of the following method of purification, metal is converted to its volatile compound which is decomposed to give pure metal? (a) Heating with stream of carbon monoxide (b) Heating with iodine (c) Liquation (d) Distillation

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56) Which of the following statements are correct? (a) A depressant prevents certain type of particle to come to the froth. (b) Copper matte contains and . (c) The solidified copper obtained from reverberatory furnace has blistered appearance due to evolution of during the extraction. (d) Zinc can be extracted by self-reduction.

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57) In the extraction of chlorine from brine............ for the overall reaction is negative. for the overall reaction is positive. for the overall reaction has negative value. for the overall reaction has positive value.

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58) Why is an external emf of more than 2.2V required for the extraction of from brine?

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59) At temperature above 1073 K, coke can be used to reduce to Fe. How can you justify this reduction with Ellingham diagram?

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60) Wrought iron is the purest form of. iron. Write a reaction used for the preparation of wrought iron from cast iron. How can the impurities of sulphur, silicon and phosphorus be removed from cast iron?

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61) How is copper extracted from low grade copper ores?

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62) Write two basic requirements for refining of a metal by Mond's process and by van Arkel Method.

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63) Although carbon and hydrogen are better reducing agents but they are not used to reduce metallic oxides at high temperatures. Why?

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64) How do we separate two sulphide ores, by froth floatation method? Explain with an example.

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65) The purest form of iron is prepared by oxidising impurities from cast iron in a reverberatory furnace. Which iron ore is used to line the furnace? Explain by giving reaction.

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66) The mixture of compounds A and B is passed through a column of by using alcohol as eluant. Compound A is eluted in preference to compound B. Which of the compounds A or B, is more readily adsorbed on the column?

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67) Why is sulphide ore of copper heated in a furnace after mixing with silica?

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68) Why are sulphide ores converted to oxide before reduction?

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69) Which method is used for refining Zr and Ti? Explain with equation.

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70) What should be the considerations during the extraction of metals by electrochemical method?

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71) What is the role of flux in metallurgical processes?

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72) How are metals used as semiconductors refined? What is the principle of the method used like germanium, silicon etc?

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73) Write down the reactions taking place in blast furnace related to the metallurgy of iron in the temperature range 500-800 K.

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74) Give two requirements for vapour phase refining.

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75) Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.

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76) Match the items of Column I with items of Column II and assign the correct code.

Column 1 Column 11

A. Pendulum B. Malachite C. Calamine D. Cryolite 1. Chrome steel 2. Nickel steel 3. 4. 5.

Codes A B C D A B C D (a) 1 2 3 4 (b) 2 4 5 3 (c) 2 3 4 5 (d) 4 5 3 2

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77) Match the items of Column I with the items of Column II and assign the correct code.

Column 1 Column 11

A. Coloured bands B. Impure metal to volatile complex C. Purification of Ge and Si D. Purification of mercury 1. Zone refining 2. Fractional distillation 3. Mond's process 4. Chromatography 5. Liquation

Codes A B C D A B C D (a) 1 2 4 5 (b) 4 3 1 2 (c) 3 4 2 1 (d) 5 4 3 2

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78) Match items of Column I with the items of Column II .and assign the correct code.

Column 1 Column 11

A. Cyanide process 1. Ultrapure Ge

B. Froth floatation process 2. Dressing of ZnS

C. Electrolytic reduction 3. Extraction of Al

D. Zone refining 4. Extraction of Au

5. Purification of Ni

Codes A B C D A B C D (a) 4 2 3 1 (b) 2 3 1 5 (c) 1 2 3 4 (d) 3 4 5 1

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79) Match the items of Column I with the items of Column II and assign the correct code.

Column 1 Column 11

A. Sapphire 1.

B. Sphalerite 2.

C. Depressant 3. Co

D. Corundum 4. ZnS

5.

Codes A B C D A B C D (a) 3 4 2 1 (b) 5 4 3 2 (b) 2 3 4 5 (d) 1 2 3 4

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80) Match the items of Column I with items of Column II and assign the correct code.

Column I Column II

A. Blisterred Cu B. Blast furnace C. Reverberatory D. Hall ? Heroult process 1. Aluminium 2.

3. Iron 4. 5.

Codes A B C D A B C D (a) 2 3 4 1 (b) 1 2 3 5 (c) 5 4 3 2 (d) 4 5 3 2

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81) Assertion (A) Nickel can be purified by Mond's process. Reason (R) Ni (00)4 is a volatile compound which decomposes at 460 K to give pure Ni.

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82) Assertion (A) Zirconium can be purified by van Arkel method. Reason (R) is volatile and decomposes at 1800K.

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83) Assertion (A) Sulphide ores are concentrated by froth flotation method. Reason (R) Cresols stabilise the froth in froth floatation method.

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84) Assertion (A) Zone refining method is very useful for producing semiconductors. Reason (R) Semiconductors are of high purity.

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85) Assertion (A) Hydro metallurgy involves dissolving the ore in a suitable reagent followed by precipitation by a more electropositive metal. Reason (R) Copper is extracted by hydro metallurgy.

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86) Explain the following (a) is a better reducing agent below 710 K whereas CO is a better reducing agent above 710 K. (b) Generally sulphide ores are converted into oxides before reduction. (c) Silica is added to the sulphide ore of copper in the reverberatory furnace. (d) Carbon and hydrogen are not used as reducing agents at high temperatures. (e) Vapour phase refining method is used for the purification of Ti.

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	Column 1	Column 11
A. Pendulum B. Malachite C. Calamine D. Cryolite		1. Chrome steel 2. Nickel steel 3. 4. 5.

Column 1	Column 11
A. Coloured bands B. Impure metal to volatile complex C. Purification of Ge and Si D. Purification of mercury	1. Zone refining 2. Fractional distillation 3. Mond's process 4. Chromatography 5. Liquation

Column 1	Column 11
A. Cyanide process	1. Ultrapure Ge
B. Froth floatation process	2. Dressing of ZnS
C. Electrolytic reduction	3. Extraction of Al
D. Zone refining	4. Extraction of Au
	5. Purification of Ni

	Column 1	Column 11
A.	Sapphire	1.
B.	Sphalerite	2.
C.	Depressant	3. Co
D.	Corundum	4. ZnS
		5.

Column I	Column II
A. Blisterred Cu B. Blast furnace C. Reverberatory D. Hall ? Heroult process	1. Aluminium 2.
	3. Iron 4. 5.

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