MODEL PAPER

1. NAVODAYA VIDYALAYA SAMITI, BHOPAL REGION
CHEMISTRY REVISION PAPER - 3
GENERAL PRINCIPLES AND PROCESSES OF ISOLATION AND THE
‘d’-AND ‘f’- BLOCK ELEMENTS
Class : XII Max. Marks: 70
Time : 3hrs.
General Instructions:
(i) All questions are compulsory.
(ii) Marks for each question are indicated against it.
(iii) Q.No.1and 8carrying 1 mark each.
(iv) Q.No.9to 18 carrying 2 marks each.
(v) Q.No.19 to 27 carrying 3 marks each
(vi) Q.No. 28 to 30carrying 5 marks each
(vii) Use log Tables, if necessary, Use of calculators is not permitted.
Answer the following questions:
1. State the role of silica in the metallurgy of copper?
2. How is cast iron different from pig iron?
3. Why is zinc not extracted from zinc oxide through reduction using CO?
4. What is meant by disproportionation?Give one example?
5. “The d1
configuration is very unstable in ions” account the following
6. Write the electronic configuration of the element with the atomic number 109?
7. Actinoid contraction is greater from element to element than lanthanoid contraction.
Why?
8. Name a member of the lanthanoid series which is well known to exhibit +4
oxidation state?
9. (a) What is the role of cryolite in the metallurgy of aluminium?
(b) Out of ‘C’ and ‘CO’, which is a better reducing agent at 673K?
10. Is it true under certain conditions Mg can reduce SiO2 and Si can reduce MgO?
What are those conditions?
11. Give an account of the extraction of silver by the cyanide process?
12. With the help of ionic equation describe what happened when
(a) pH of a solution of dichromate ion is raised
(b) Potassium manganate is electrochemically oxidized.
13. Account for the following
(a) Zn+2
salts are white while Cu+2
salts are blue.
(b) Cr+3
is strongly reducing while Mn+3
is strongly oxidising
14. Explain
(a) The enthalpies of atomization of the transition metals are high.
(b) Transition metals and their many compounds act as good catalyst
15. (a) Why is Cr+2
reducing and Mn3+
oxidizing when both have d4
configuration?
(b) Why is the E0
value for the Mn+3
/Mn+2
couple much more positive than that
for Cr+3
/Cr+2
or Fe3+
/Fe+2
? Explain.
16. Calculate the magnetic moment of a divalent ion in aqueous solution if its atomic
number is 25.
17. What are the characteristics of the transition elements and why are they called
transition elements? Which of the d-block elements may not be regarded as the
transition elements?
18. Complete the following
(a) C2O4
2-
+ MnO4
-
+ H+
→
(b) 2I-
+ S2O8
2-
→
19. Write short notes on the following giving one example
(i) Roasting (ii) Calcination (iii) Smelting
K.G.MALLIKARJUN,JNV,ANTHAPUR
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2. 20. (a) What is meant by chromatography?
(b) The value of ΔfG0
for formation of Cr2O3 is –540kJ/mol and that of Al2O3 is
–827kJ/mol. Is the reduction of Cr2O3 possible with Al?
21. (a) Account for the irregular variation of ionization of enthalpies in the
(first and second) First transition series.
(b) Calculate the ‘spin only’ magnetic moment of bivalent ion (z=26)
(c) Give the ground and excited state configuration in crystal field
theory for [Ti(H2O)6]3+.
Atomic number Ti=22.
22. (a) Explain Mond process for refining Nickel?
(b) Describe Van Arkel method for refining Zirconium or Titanium?
23. Give the preparation of KMnO4 from pyrolusite and draw the structure of
Permanganate and manganate ions?
24. (a) What is lanthanide contraction and give its consequences?
(b) Differentiate the properties of lanthanides and actinides?
25. Outline the principles of refining of metals by the following methods (i) Zone
refining (ii) Electrolytic refining (iii) Vapour phase refining?
26. (a) Why is the reduction of a metal oxide easier if the metal formed is in liquid
state at the temperature of reduction?
(b) How zinc is extracted from zinc oxide?
27. (a) In the following which show colour Sc+3
, Ti+3
, V+4
and Zn+2
(b) Draw the structures of chromate ion and dichromate ion?
28. (a) Explain (i) Zone refining (ii) Column chromatography
(b) How can you separate alumina from silica in a bauxite ore associated with
silica? Give equations
29. What is the Ore of K2Cr2O7 and give the equations involved in the
preparation. Give the reactions of K2Cr2O7 with KI and H2S .
30. Explain the following ;-
1.Variable oxidation state
2.Magnetic nature
3.Colour of the metal ions
4.Ionization enthalphy.
5.Interstitial compounds
K.G.MALLIKARJUN,JNV,ANTHAPUR
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