CHEMISTRY SAMPLE PAPER - I
CLASS - XII
Time : Three Hours Max. Marks : 70
1. All questions are compulsory.
2. Question nos. 1 to 8 are very short answer questions and carry 1 mark each. 3. Question nos. 9 to 18 are short answer questions and carry 2 marks each. 4. Question nos. 19 to 27 are also short answer questions and carry 3 marks each 5. Question nos. 28 to 30 are long answer questions and carry 5 marks each 6. Use log tables if necessary, use of calculators is not allowed. (1) Why is ferric chloride preferred over potassium chloride in case of a cut leading to bleeding? 1 (2) Why does a tetrahedral complex of the type [MA2 B2] not show geometrical isomerism? 1 (3) How do you account for the miscibility of ethoxyethane with water. 1 (4) Give the IUPAC name of the organic compound 1
(CH3)2 C CH C CH3
= − −
(5) Name the monomers of nylon 2 or nylon 6 ploymer. 1
(6) Give one example of an artificial sweetener used by the diabetic patients. 1 (7) Direct nitration of aniline is not carried out. Explain why? 1 (8) What type of linkage holds together the monomers of D.N.A.? 1 (9) Examine the illustration of a portion of the defective crystal given below and answer the following questions. (5)
(i) What are these type of vacancy defects called?
(ii) How is the density of a crystal affected by these defects? (iii) Name one ionic compound which can show this type of defect in the crystalline state (iv) How is the stoichiometry of the compound affected? 2
10. Analysis shows that a metal oxide has the empirical formula M0.96 O1.00. Calculate the percentage of M2+ and M3+ ions in this crystal? 2
In an ionic compound the anion (N¯) form cubic close type of packing. While the cation (M+) ions occupy one third of the tetrahedral voids. Deduce the empirical formula of the compound and the coordination number of (M+) ions. 2
11. Given below is the sketch of a plant for carrying out a process. (i) Name the process occurring in the above plant.
(ii) To which container does the net flow of solvent take place? (iii) Name one SPM which can be used in this plant.
(iv) Give one practical use of the plant. 2
12. Write the chemical equations for all the steps involved in the rusting of iron. Give any one method to prevent rusting of iron. 2
13. A metal ion Mn+ having d4 valence electronic configuration combines with three didentate ligands to form a complex compound. Assuming
(i) draw the diagram showing d orbital splitting during this complex formation. (ii) write the electronic configuration of the valence electrons of the metal Mn+ ion in terms of t2g and eg. (iii) what type of hybridisation will Mn+ ion have?
(iv) name the type of isomerism exhibited by this complex. 2 14. A mixed oxide of iron and chromium FeOCr2O3 is fused with sodium carbonate in the presence of air to form a yellow coloured compound (A). On acidification the compound (A) forms an orange coloured compound (B), which is a strong oxidising agent. Identify
(i) the compounds (A) and (B)
(ii) write balanced chemical equation for each step 2
15. An optically active compound having molecular formula C7H15Br reacts with aqueous KOH to give a racemic mixture of products. Write the mechanism involved for this reaction. 2 (6)
16. Write the formula of main product formed in the following chemical reactions. (i) (CH3)2 CH-C1
(ii) CH3Br + AgF
(iii) CH3CH2Br + Nal
17. Differentiate the following pair of polymers based on the property mentioned against each. (i) Novolac and Bakelite (structure)
(ii) Buna-s and Terylene (intermolecular forces of attraction) 2 18. In order to wash clothes with water containing dissolved calcium hydrogencarbonate, which cleaning agent will you prefer and why: soaps or synthetic detergents? Give one advantage of soaps over synthetic detergents. 2 19. Heptance and octane form an ideal solution at 373 K, The vapour pressures of the pure liquids at this terperature are 105.2 KPa and 46.8 KPa...
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