CBSE Guess Paper: 2011
Class- XII
(Chemistry)

Time Allowed: 3 hours
Maximum Marks: 70
INSTRUCTIONS:
1. Q- 1-8 CARRY 1 MARKS EACH
2. Q- 9-18 CARRY 2 MARKS EACH
3. Q 19-27 CARRY 3 MARKS EACH
4. Q-28-30 CARRY 5 MARKS EACH
5. Give answer according to marks in order to save time..

Section-A

Q.1. WHAT IS THE NATURE OF CRYSTRAL DEFECT PRODUCED WHEN SODIUM CHLORIDE IS DOPED WITH MAGNESIUM CHLORIDE? (1 Marks)

Q.2. A REACTION IS 50% COMPLETE IN 2 HOURS AND 75% IN 4 HOURS WHAT IS ORDER OF THE REACTION?. (1 Marks)

Q.3. DRAW THE STRUCTURE OF SEMICARBAZONE OF CYCLOBUTANONE (1 Marks)

Q.4. WHAT HAPPEN WHEN FERROMAGNETIC SUBSTANCE IS SUBJECTED TO HIGH TEMPRATURE?.(1 Marks)

Q.5. WHAT IS RATE CONSTANT AND HOW DOES ITS VALUES VARY WITH REACTANT CONCENTRATION (1/2 + 1/2 Marks)

Q.6. WHY IS SULPHURIC ACID NOT USED DURING THE REACTION OF ALCOHOLS WITH KI? (1 Marks)

Q.7. IN THE RING TEST FOR IDENTIFICATION OF NITRATE ION ,WHAT IS FORMULA OF THE COMPOUND RESPONSIBLE FOR BROWN RING
FORMED AT THE INTERFACE OF 2 LIQUIDS?.(1 Marks)

Q.8. WHAT DO YOU UNDERSTAND BY TERM GLYCOSIDIC LINKAGE?.(1 Marks)

Section-B

Q.9. ALUMINIUM CRYSATLISES IN A CUBIC CLOSE PACKED STRUCTURE .ITS METALLIC RADIUS IS 125pm
A. WHAT IS LENGHT OF SIDE OF THE UNIT CELL. (1 Marks)
B. HOW MANY UNIT CELLS ARE THERE IN 1 meter cube of aluminium. (1 Marks)

Q.10. corrosion is essentially an electrochemical phenomenon .with the help of digram expalin the reactions occuring during the corrosion of iron. (2 Marks)

Q.11. A. can the substance act both as colloid and crstalloid. (1 Marks)
B. WHY HYDROPHILLIC SOLS ARE MORE THAN HYDROPHOBIC SOLS (1 Marks)

Q.12. A. COMMENT " COLLOID IS NOT A SUBSTANCE BUT A STATE OF SUBSTANCE". (1 Marks)
B. EXPLAIN WHY DELTAS ARE FORMED WHERE RIVER AND SEA WATER MEET. (1 Marks)

Q.13. A. WHY IS Bi(V) IS STRONGER OXIDISNG AGENT THAN Sb(V). (1 Marks)
B. DRAW STRUCTURE OF PEROXODISULPHURIC ACID(1 Marks)

OR

WRITE CHEMICAL EQUATIONS FOR THE FOLLOWING
1. ORTHOPHOSPHORUS ACID IS HEATED.(1 Marks)
2. PTF6 AND XENON ARE MIXED TOGETHER.(1 Marks)

Q.14. UNLIKE PHENOLS, ALCOHOLS ARE EASILY PROTONATED. (2 Marks)

Q.15. WRITE A SHORT NOTE ON
A. COUPLING REACTION (1 Marks)
B. HOFMANN'S BROMAIDE REACTION (1 Marks)

Q.16. ACCOUNT FOR THE FOLLOWING
A. CHLORINE WATER HAS BOTH OXIDIZING AND BLEACHING PROPERTIES (1 Marks)
B. ON ADDITION OF OZONE GA TO KI AOLUTION,VOILET VAPOURS ARE OBTAINED. (1 Marks)

Q.17. HOW WILL YOU DISTINGUISH BETWEEN
A. ETHYLAMINE AND ANILINE. (1 Marks)
B. METHYL AMINE AND DIMETHYLAMINE (1 Marks)

Q.18. GIVE THE MECHANISM OF PREPARATION OF ETHOXYETHANE FROM ETHANOL (2 Marks)

SECTION -C

Q.19. A COPPER-SILVE CELL IS SET UP . THE COPPER ION CONCENTRATION IN IT IS 0.10 M. THE CONCENTARTION OF SILVER ION IS NOT KNOWN. THE CELL POTENTIAL MEASURED IS 0.422V DETERMINE THE CONCENTRATION OF SILVER ION IN THE CELL (3 Marks)

Q.20. DURING A NUCLEAR EXPLOSION ,ONE OF THE PRODUCT IS 90SR WITH THE HALF LIFE OF 28.1 YEARS .IF 1UG OF 90SR WAS ABSORBED IN THE BONES OF NEWLY BONE BABY INSTEAD OF CALCIUM ,HOWM MUCH OF IT WILL REAMIN AFTER 10 YEARS AND 60 YEARS IF IT IS NOT LOST METABOLICALLY. 3(PLEASE REFER QUETION NO. 17 FROM NCERT FOR PROPER STATEMENT IN TERMS OF SYMBOLS).

Q.21. A NAME THE METHOD USED FOR REFINING OF
A. NICKEL (1/2 Marks)
B. ZIRCONIUM (1/2 Marks)
C. THE EXTRACTION OF AU BY LEACHING WITH NACN INVOLVES BOTH OXIDATION AND REDUCTION .JUTIFY GIVING WEQUATIONS. (2 Marks)

Q.22. HOW CAN YOU PREPARE XEOF4 AND XEO3 FROM XEF6 . (2 Marks)
B. HOW ARE INTERHALOGEN COMPOUNDS PREPARED?. (1 Marks)

Q.23. A. THE HEXAAQUAMAGANESE (II) ION CONTAINS FIVE UNPAIRED ELECTRONS,WHILE THE HEXACYANOMANGANESE(II) IONS ONLY CONTAIN ONE UNPAIRED ELCTRON.EXPLAIN USING CRYSTAL FIELF THEORY. (2 Marks)
B. WHAT IS BASIS OF FORMATION OF THE SPECTROCHEMICAL SERIES. (1 Marks)

Q.24. A. WHICH WILL HAVE HIGHRE BIOLING POINT - 1-CHLOROPENTANE OR 2-CHLORO-2METHYLBUTNAE. (1 Marks)
B. GIVE REASON: p-nitrochlorobenzene UNDERGOES NUCLEOPHILIC SUBSTITUTION FASTER THAN CHLOROBENZENE. EXPLAIN GIVING RESONATING STRUCTTURE AS WELL. (2 Marks)

Q.25. A. HOW DO YOU EXPLAIN THE AMPHOTERIC NATIURE OF AMINO ACIDS. (2 Marks)
B. WRITE REACTION WHEN GLUCOSE IS TREATED WITH ACETIC ANHYDRIDE. (1 Marks)

Q.26. WHAT ARE BIODEGRADABLE POLYMER. GIVE AN EQUATION OF BIODEGRADABLE ALIPHATIC POLYESTER (1+1 Marks)
B. WHAT IS THE ROLE OF BEZOYL PEROXIDE IN POLYMERISATION O ETHENE. (1/2 Marks)
C. HOW DO YOU EXPLAIN FUNCTIONALITY OF A MONOMER. (1/2 Marks)

Q.27. CLASIFY DETERGENTS GIVING AN EAMPLE IN EACH CASE. (3 Marks)

OR

A. LOW LEVEL OF NONADRENALINE IS THE CAUSE OF DEPRESSION.WHAT TYPE OF DRUGS ARE NEDDED TOCURE THIS PROBLEM?.NAME TWO DRUGS (1/2+1 Marks).
B. WHAT IS TINCTURE OF IODINE (1/2 Marks)
C. DEFINE CHEMOTHERAPY (1 Marks)

SECTION -D

Q.28. "THE OSMOTIC PRESSURE OBSERVED WHEN BENZOIC ACID IS DISSOLVED IN BENZENE IS LESS THAN EXPECTED VALUE". COMMENT (2 Marks)
B. A DECIMOLAR SOLUTION OF POTASSIUM FERROCYANIDE IS 50% DISSOCIATED AT 300K .CALCULATE THE OSMOTIC PRESSURE OF THE SOLUTION. (3 Marks)

OR

A. DERIVE AN EXPRESSION TO EXPRESS THE REALTIVE LOWERING OF VAPOUR PRESSURE FOR A SOLUTION IS EAQUAL TO THE MOLE FRACTION OF THE SOLUTE IN IT WHNE THE SOLVENT ALONE IS VOLATILE. (3 Marks)

B. THE ELEMENTS A AND B FORM PURELY COVALENT COMPOUNDS HAVING MOLECULAR FORMULA AB2 AND AB4.WHEN DISSOLVED IN 20 G OF BENZENE,1 g OF AB2 LOWERS THE FREEZING POINT BY 2.3 K WHEREAS I g OF AB4 LOWERS IT BY 1.3K. THE MOLAL DEPRESSION CONSTANT FOR BENZENE IS 5.1K KG/MOL CALCULATE THE ATOMIC MASS OF A AND B. (2 Marks)

Q.29. A. DESCRIBE HOW POTASSIUM DICHROMATE IS MADE FROM CHROMITE ORE AND GIVE THE EQUATIONS FOR THE CHEMICAL REACTION INVOLVED. (2 Marks)

B. WRITE THE BALANCED IONIC EQUATIONS FOR REACTING IONS TO REPRESENT THE ACTION ACIDIFIED POTASSIUM DICHROMATE ON:
1. POTASSIUM IODIDE SOLUTION (1 Marks)
2. ACIDIFIED FERROUS SULPHATE SOLUTION.(1 Marks)
C. GIVE REASON:
THE ENTHALIPIES OF ATOMISATION OF TRANSITION ELEMENTS ARE HIGH .(1 Marks)

Q.30. AN ORGANIC COMPOUND WITH MOLECULAR FORMULA C9H10O( C-9 ,H-10,O) FORMS2,4-DNP DERIVATIVE ,REDUCES TOLLENS REAGENT AND UNDERGOES CANNIZZARO REACTION. ON VIGOROUS OXIDATION IT GIVES 1,2-BENZENEDICARBOXYLIC ACID.IDENTIFY THE COMPOUND. (3 Marks)
B HOW WILL YOU CONVERT
1. BENZOIC ACID TO M-NITROBENZOIC ACId (1 Marks)
2. ETHANOL TO ACETONE. (1 Marks)