http:// www.cbseguess.com/ Give an example of heterogeneously catalysed reaction? 1 2. What is the oxidation number of Ni in [Ni(CO) 4 ]? 1 3. Give the IUPAC name of the following compound 1 4. Account the following: o-nitrophenol has lower boiling point than p-nitrophenol. 1 5. Why are primary amines are higher boiling than tertiary amines? 1 6. Name the purines present in DNA. 1 7. Write formulae of the monomers of polythene and Teflon? 1 8. Why is bithional is added to the toilet soap? 1 9. An element having bcc structure with a cell edge of 288pm. If the density of the element is 7.2g/cm 3 , what is atomic mass of the element? 2 10. Explain the following terms with suitable example: i) F-centres ii) Schottky defect. 2 ---------------------------------------------------------------------------------------------------- --- www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com
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Give an example of heterogeneously catalysed reaction? 1
2. What is the oxidation number of Ni in [Ni(CO)4]? 1
3. Give the IUPAC name of the following compound
1
4. Account the following:
o-nitrophenol has lower boiling point than p-nitrophenol. 1
5. Why are primary amines are higher boiling than tertiary amines? 1
6. Name the purines present in DNA. 1
7. Write formulae of the monomers of polythene and Teflon? 1
8. Why is bithional is added to the toilet soap? 1
9. An element having bcc structure with a cell edge of 288pm. If the density of the element
is 7.2g/cm3, what is atomic mass of the element? 2
10. Explain the following terms with suitable example:
i) F-centres ii) Schottky defect. 2
11. Molarity or molality, which is the best method to express concentration of a solution?
Why? 2
12. How much electricity in terms of Faraday is required to produce,
13. Which is more basic La(OH)3 or Lu(OH)3? Why? 2
14. a) Use valance bond theory predict the geometry and magnetic behaviour of [Co(NH3)6]+3
ion .[At.No. of Co= 27]
b) Write the IUPAC name of [Pt(NH3)2Cl2] 2
15. Define the following terms:
a) Recemic mixture b) Resolution c) Enantiomers 2
16. What happens when: (Give chemical reactions)
a) Cyclohexanol is treated with Thionyl chloride?
b) p-Hydroxybenzyl alcohol is heated with HCl? 2
17. Distinguish between the terms homopolymer and co polymer and give an example of each. 2
18. What do you understand by broad spectrum antibiotics? Give one example. 2
19. At 300K, 36g of glucose ( C6H12O6) present per liter in its aqueous solution has an osmotic pressure of 4.98 bars. If the osmotic pressure of another solution of glucose is 1.52 bar at the same temperature, what would be its concentration? 3
20. Write the Nernst equation. Calculate e.m.f of the following cell at 250C:
Pt(s)/Br2(l)/Br-(0.010M)//H+(0.030M)/H2 (1 bar)/Pt(s) [Given: Eo Br2/Br- = +1.08 V] 3
21. a) Why is alum added to water for purification?
b) Explain why deltas are formed where river and sea water meet.
c) Describe the preparation of a colloidal solution of arserous sulphide in water. 3
22. Outline the principles of refining of metals by the following methods:
28. a) Mention the factors that affect rate of a chemical reaction.
b) A first order reaction takes 69.3 minutes for 50% completion. Set up an equation for determining the time required for 80% completion of this solution.
c) Show that in a first order reaction, time required for completion of 99.9% is 10 times of half-life (t1/2) of the reaction. 5
29. Account for the following:
a) PH3 is a weaker base than NH3.
b) SF6 exists but SH6 does not.
c) ClF3 exists but FCl3 does not.
d) H3PO3 is diprotic acid.
e) ICl more reactive than I2. 5
30. a) An organic compound with the molecular formula C9H10O forms 2,4-DNP derivative,
reduces Tollen’s reagent and undergoes Cannizaro reaction. On vigorous oxidation,
it gives 1,2-benzene dicarboxylic acid. Identify the compound.
b) Write the steps and conditions involved in the following conversions:
i) Acetophenone to 2-phenyl-2-butanol.
ii) Propene to acetone. 5
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General instructions:All questions are compulsory.Marks for each question are indicated against it.Questions number 1to 8 are very short –answer questions, carrying 1 mark each. Answer these in one word or about one sentence each.Questions number9 to18 are short –answer questions, carrying 2 marks each. Answer these in about 30 words each.Questions number19 to27 are short –answer questions, carrying 3 marks each. Answer these in about 40 words each.Questions number28 to30 are long-answer questions of 5 marks each. Answer these in about 70 words each.
1 Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show cleavage property?
2 What kind of adsorption is represented by the following graph : (1)
T
x
M
3 Give one method of preparation of nitrous oxide. (1)4 What do you understand by ‘chelate ligand5 What is Saytzeff rule? (1)6 How will you convert Methyl iodide to Dimethylamine7 Why are primary amines higher boiling than tertiary amines? 8 Illustrate with equations, how is nylon obtained from caprolactum? 9 The vapour pressure of dilute aqueous solution of glucose (C6H12O6) is 750 mm of mercury at 373K. Calculate1) Molality2) Mole fraction of the solute (2)
10 Iron and Silver are used to make electrochemical cell by using a salt bridge to join a half cell containing 0.01
M Fe2+ (aq) in which a strip of iron has been immersed to a second half cell which contains 0.1 M Ag2+ (aq) in which a strip of Ag has been immersed ? A voltmeter is connected between the two metal strips:
E°Fe²+/Fe = – 0.44 V E°Ag²+/Ag = + 0.80 V
(a) Write the name of the cathode and anode.(b)Calculate the emf of cell
11 30% of a first order reaction was completed in 90 minutes. Calculate the time taken for the reaction to go to 90% completion? (2)12 A metal complex having the molecular formula Cr(NH3)4Cl2Br has been isolated in the two forms A and B.
A+AgNO3white ppt soluble in dilute aqueous ammonia B+ AgNO3Pale yellow ppt insoluble in dilute ammonia.
(i) Write the formula of the complexes A and B.(ii) What is the hybridisation of the chromium in both complexes? (2)
13 Apply VSEPR theory to deduce the structures of XeF4 and XeF6. (2)14 Write name reactions:
(i) Dow’s process (ii) Kolbe’s synthesis (2)15 Give reasons:
(i) Phenols do not undergo reactions involving cleavage of COH bond.(ii) Preparation of C2H5Cl is preferred with SOCl2 rather than PCl5 and PCl3. (2)
16 What is PHBV? Write its preparation. (2)17 Write two reactions of glucose with different reagents to confirm the presence of aldehydic group and secondary alcoholic group. (2)18 What are anomers ? Give two points of difference between two anomers of glucose. (2)19 What are defects? Give a brief account of defects. (3)20 75.2 g of phenol is dissolved in a solvent in which it undergoes association. Kf = 14, if the depression in freezing point is 7 K. What is the % association of phenol ? (3)21 Chromium metal can be plated out from acidic solution containing CrO3 according to following reaction- [At mass of Cr=52]
Calculate the mass of chromium that will be plated out by 12000 C of charge. (3)
22 Classify and explain different types of colloids. (3)23 (a)What are the factors which affect rate of reaction? (b) What is pseudo first order reaction? (2+1)
24 What is hydrometallurgy? Explain with the help of Mac Aurthur Forrest cyanide process. (3)25 (i) Arrange in order of property indicated : CH3CH2CH2CH2Br, (CH3)3 Br, (CH3)3 CHCH2 Br (Increasing boiling point)
(ii)CH3F, CH3I, CH3Cl, CH3Br (nucleophilic substitution)(iii) What is racemisation? (1+1+1)
26 Accomplish the following conversions :-------------------------------------------------------------------------------------------------------
(i) Zn, Cd and Hg are not considered as transition elements.(ii) Scandium is a transition element but Zinc is not.(iii) Silver atom has completely filled d orbital (4d10) in its ground state, yet it is transition element(iv) Transition metals have high melting and boiling points.(v) Transition elements exhibit higher enthalpies of atomization. (5)
ORDescribe how Potassium dichromate is made from Chromite ore. Give the equations for the Chemical reactions involve. (b) Write balanced ionic equations for reacting ions to represent the action of acidified Potassium dichromate solution on:(i) Potassium iodide solution [ii] iron (II) solution [iii] H2S (c) The chromates and dichromates are interconvertible in aqueous solution depending upon pH of the solution. (5)29 (a) Primary alkyl halide C4H9Br (a) reacted with alcoholic KOH to give compound (b).Compound (b) is reacted with HBr to give (c) which is an isomer of (a).When (a) is reacted with sodium metal it gives Compound (d),C8H18 which is different from the compound formed when n-butyl bromide is reacted with sodium .Give the structural formula of (a) and write the equations for all the reactions. (b) An organic compound ‘A’ with molecular formula C5H5O . It does not reduce Tollen’s or Fehling’s reagent but forms a bisulphite compound. It also gives iodoform tests. Identify A
OR(a)An organic compound ‘A’ with molecular formula C5H8O2 is reduced to n-pentane on treatment with Zn-Hg/HCI. ‘A’ forms a dioxime with hydroxylamine and gives a positive iodoform test and Tollen’s test. Identify the compound A and deduce its structure.(b) An aromatic compound A on treatment with aqueous ammonia and heating forms compound B which on heating with Br2 and KOH forms a compound C of molecular formula C6H7N .Write the structures and IUPAC names of compounds A,B,C. 30 Explain:(a) why PCl3 fumes in air?(b) Why oxygen does not show +6 state?(c) Why higher concentration of O3 are explosive?(d) Why Cl2 act as bleaching agent?(e) How is xenon trioxide is prepared. Draw its structure? OR
(i) Why all the bonds in PCl5 are not of equal length?(ii) Why H2S is less acidic than H2Se ?(iii) How is O3 estimated quantitatively?(iv) Why fluorine has lower electron gain enthalpy than chlorine?(v) SF6 is highly stable.
Sample Paper – 2011Class – XII
Subject –ChemistryTIME ; 3HR First book
Selected Question
1) ALL QUESTION ARE COMPOLSORY2) USE LOG TABLE IF NECESSARY
Q.1 FILL THE BLANKS
1. XeF6+NaF -----
2. Zn+V.DIL HNO3 ----
3.SCl2+NAF ----
4.POCl3+H2O ----
P4O10
5.HNO3 ---HEAT--------
Q.2 GIVE THE METHIOD OF PREP.OF XeOF4 & XeO3 FROM XeF6
Q.3 DRAW THE STRUCTURE OF 1)H2SO5 2)H2S2O8
3)HOClO3 4) BrF3 5)XeF6
Q.4 GIVE THE ANSWER OF FOLL:
1) NOBAL GAS ELEMENT FROM COMPOUND WITH ONLY FLOURIN & OXYGEN
2) WHY ALL BOND IN PCL5 ARE NOT EQUAL IN LENGTH-------------------------------------------------------------------------------------------------------
1) DESCRIBE THE MANUFACTHRING OF H2SO4 BY CONTACT PROCESS?
2) WHY DOES R3P=0 EXIST BUT R3N=0 DOES NOT ?
3) HOW RED PHOSPHOROUS IS OBTAINED FROM WHITE PHOSPHORUS ?
4) SF4 CAN BE HYDROLYS BUT SF6 CAN NOT ?
5) O3 ACT AS POWER OXIDISING AGENT
6) GIVE REASON, WHICH PREMPTED BARTTLET TO PREPARE 1ST NOBAL GAS COMPOUND.
Q.6 GIVE THE ANSWER OF FOLL
1) FLOURINE DOES NOT SHOW VARIABLE O.S WHILE OTHER MEMBER OF HALOGEN FAMILY EXHIBIT VARIABLE O.S
2) HF IS STORED IN GLASS BOTTLE BUT IS KEPT IN WAX BOTTLE.
Q.7 EXPLAIN WITH REASON
1) THE ENTHALPY OF ATOMISATION OF T.M ARE HIGH2) CHEMISTRY OF ALL THE LANTHANOIDS IS QUITE SIMILAR3) CRO4
2- IS STRONG OXIDIZING AGENT WHILE MNO42- IS NOT
Q.8 GIVE REASON :
1) CE4+ IS USED AS OXIDISING AGENT IN VOLUMETRIC ANALYSIS.-------------------------------------------------------------------------------------------------------
3) WHY IS THE COMPLAX [TI(H2O)6]3+ ION IS COLOURED EXPLAIN ON THE BASIS OF ELECTRON IN THE D-ORBITALS
4) WHY IS THE GEO. ISOMERISM NOT POSSIBLE IN TETRAHEDRAL COMPLEXES HAVING TWO DIFFERENT TYPE OF UNIDENTATED LEGANDS COORDINATED WITH THE CENTRAL METAL ION
5)WRITE IUPAC NAME OF A) [Ni(NH3)6]Cl2 B) [CO(NH3)4(H2O)Cl]Cl2
C) [COCl2(CN)2]CL
Q.12
DISCUSS THE SPLITING OF AT ORBITAL IN OCTAHEDRAL AND
D) WRITE FREUNDLICH ISOTHERM EQUATION AT LAW PRESSURE ?
E) HOW YOUN CAN PREPARE AS2S3SOL & AU SOL & FE(OH) SOL
BY CHEMICAL METHOD
F) DESCRIBE SOME FEATRES OF CATALYSIS BY ZEOLITES ?
G) ROLE OF DESOPTION IN THE PROCESS OF CATALYSIS ?
Q.17 GIVE THE ANSWER OF FOLL
A) RATE OF CHEMICAL REACTION DOUBLES FER AN INCREASE OF 10K IN ABSOLUTE TEMP. FROM 298K CALULATE EA
B) THE FOLLWING DATA WERE OBTAINED DURING THE 1ST ORDER THERMAL
DECOMPOSISTION OF SO2CL2 AT ACONSTANT VOL.
SOCL2(G) -- SO2(G) +CL2(G)
EXE. TIME/S-1 TOTAL PRESSURE / ATM
1. 0 0.5
2. 100 0.6
CALCULAT THE RATE OF REACTION TOTAL PRESSURE IS 0.65 ATM
C) SHOW THAT IN CASE OF FIRST ORDER REACTION ,THE TIME TAKEN FOR COMPLECTION OF 99.9% REACTION IS TEN TIME THE TIME REQUIRED FOR HALF CHANGE OF THE REACTION
Q.22 WHAT ARE FUEL CELLS DISCUSS H2-O2 FUEL CELL LIST TWO
ADVANTAGE OF FUEL CELLS OVER OTHER CELLS
Q.23 PREDICT THE PRODUCT OF ELECTROLYSIS OBTAINED AT THE
ELECTRODES IN CASE WHEN ELECTROD USED ARE OF PT
A) AN AQUEOUS SOL. OF AgNO3
B) AN AQUEOUS SOL. OF H2SO4
Q.24 HOW DOES THE MOLAR CONDUCTIVITY VARY WITH CONC. FOR
A) WEAK ELECTROLYTE B) STRONG ELECTROLYTE
Q.25 WRITE CELL REACTION WHICH ACCURS IN LEAD STRONGE BATTERY
A) WHEN BATTERY IS IN USE B) WHEN BATTERY IS ON CHARGING
Q.26 STATE HENRY’S LAW & MENTION TWO IMP.APPLICATION
Q.27 WHAT IS MEANT BY +VE & -VE DEVIATION FROM RAOULT’S LAW &
& HOW IS THE SING OF DELTA MIX RELATED TO +VE & -VE DEVIATION FROM RAOULTSS LAW
Q.28 DEF: A) MOLE FRACTION B) MOLALITY C) MOLARITY
Q.29 45G OF ENTHYULENE GLYCOL (C2H6O2) IS MIXED WITH 600G OF WATER
CAL. A) THE FREEZING PT. DEPRESION
B) FREEZING POINT OF SOLUTION ( Given Kf= 1.86 KKgMOL)
Q.30 STATE THE CONDITION RESULTING IN REVERSE OSMOSIS ?
Q.31 WHAT MAKES A GLASS DIFFERENT FREM A SOLID SUCH AS QUARTZ
UNDER WHAT CONDITION COULD QUARTZ BE CONVERTED INTO
GLASS.
Q.32 FOR DETERMINING MOLAR MASS OF MACROMOLECULAR SUBSTANCE IN SOL; THE OSMOTIC PRESSURE MEASURMENT METHOD IS PREFERRED OVER MEASURMENT METHOD OF ANY OTHER COLLAGATIVE OF SOL. GIVE TWO REASONS FOR IT.
Q.33 WHAT WOULD BE THE VALUE OF VAN’T HOFF FACTORS FOR DILUTE SOLUTION OF K2SO4 IN WATER -------------------------------------------------------------------------------------------------------
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 mark each.4. Question Nos. 19 to 27 are short answer questions and carry 3 mark each.5. Question Nos. 28 to 30 are long answer questions and carry 5 mark each.6. Use log tables if necessary, use of calculators is not allowed.
Q1) How many effective sodium ions are located at the centres of the faces of a unit cell in sodium chloride crystal?
Q2) What do you observe when Red Blood corpuscles are placed in (i) 1% NaCl Solution, (ii) 0.5% NaCl Solution?
Q3) Give reason for the “blue colour of the sky”.
Q4) Give the role cryolite in the metallurgy of aluminium.
Q5) Write I.U.P.A.C. name for,
Q6) Name the monomer from which Nylon – 6 is manufactured.
(i) Hexagonal Close packing and cubic close packing.(ii) Tetrahedral void and Octahedral void.
Q10) Niobium crystallizes in body centred cubic structure. If density is 8.55 gcm-3, calculate atomic radius of niobium using its atomic mass 93U.
Q11) 45g of ethylene glycol (C2H6O2) is mixed with 600gm of water. Calculate (a) the freezing point depression and (b) the freezing point of the solution.
Q12) The standard electrode potential for Danial Cell is 1.1V. Calculate the Standard Gibbs energy for the reaction : ∆rGo = - RT lnK
Q13) Why do the transition elements exhibit higher enthalpies of atomization?
Q14) [NiCl4]2- is paramagnetic while [Ni(CO)4] is diamagnetic though both are tetrahedral. Why?
Q15) What happens when :
(i) Ethyl chloride is treated with aqueous KOH?(ii)Chlorobenzene is subjected to hydrolysis.
Q16) Explain why :1. The dipole moment of chloroform is lower than that of cyclohexyl chloride?2. Grignard reagents should be prepared under anhydrous conditions?
Q17) Explain the difference between Buna – N and Buna – S.
Q18) Define thermoplastics and thermosetting polymers with two examples of each.
Q19) What are food preservatives? Give one examples.
Q20) Calculate the mole fraction of ethylene glycol (C2H6O2) in a solution containing 20% of C2H6O2 by mass.
Q21) Depict the galvanic cell in which the reaction, Zn(s) + 2Ag+(aq) Zn2+(aq) + 2Ag(s) takes place.(i) Which of the electrode is negatively charged?(ii) The carriers of the current in the cell.(iii) Individual reaction of each electrode.
Q22) Distinguish between physisorption and chemisorptions.
Q23) Why is the extraction of copper from pyrites more difficult than that from its oxide are through reduction?
Q24) What happens when :(i) Concentrated H2SO4 is added to calcium floride?(ii) SO3 is passed through water?
Q25) Write balanced equation for the following:(i) NaCl is heated with sulphuric acid in the presence of MnO2.(ii) Chlorine gas is passed into a solution of NaI in water.
Q26) Write the equation involved in the followed reactions :
1) NaClO3 is treated with SO2.2) Ca3P2 is treated with water.
(b) Give reason :(i) CO2 is gas while SiO2 is solid.(ii) SbCl5 is more covalent than SbCl3.(iii) Interhalogen compounds are more reactive than pure halogen.
Q29) Account for the following :
(a) Eo for Mn3+/Mn2+ couple is more positive than for Fe3+/Fe+.(b) Zn2+ salts are white while Cu2+ salts are coloured.(c) Ce3+ can easily oxidized to Ce4+.(d) Zr and Hf exhibit almost similar properties.(e) Transition elements show variable oxidation states.
OR(a) Give the chemical equation involved in the reparation of potassium dichromate from chromite
ore.(b) Write down the effect of PH on K2Cr2O7.(c) Define lanthanoid contraction.
Q30) Calculate the EMF of the cell at 25oC(a) Ni/Ni2+ (0.1M) // Cu2+ (0.1M) / Cu
EoNi2+/Ni = - 0.25 VEoCu2+ / Cu = 0.34 V
(b) How many hours does it take to reduce 3 mole of Fe3+ to Fe2+ with 2 Ampere current 1F = 96500 e-
ORConductivity of 0.00241 M acetic acid is 7.896 × 10-5 SCm-1. Calculate Molal conductivity if m for CH3COOH is 390.55 cm2mol-1. What is dissociation constant?
Sample Paper – 2011Class – XII
Subject - Chemistry (Theory)
TIME : 3 Hours M.M. 70
General instructions :-
1. All questions are compulsory -------------------------------------------------------------------------------------------------------
2. Internal choices has been provided in some questions you have to attempt only one of the choice in such questions.
3. Q.No 1 to 8 are very short answer type questions, carrying one mark each.4. Q. No. 9 to 18 are short answer type questions, carrying two mark each.5. Q.No. 19 to 27 are also short answer questions, carrying three mark each.6. Q.No. 28 to 30 are long answer type questions, carrying five mark each.7. Use of calculators is not permitted. However you may use log tables, if necessary.
Q.1 What is an azeotrope?
Q.2 People living at high altitude generally suffer from anoxia , Explain.
Q.3 Define limiting molar conductivity .
Q.4 “A greater insight in to the energetic and mechanistic aspects of reactions”. Explain the above statement which was given by “Max Trautz” and William Lewis”
Q.5 Define the term mutarotation
Q.6 Name one Biodegradable aliphatic polyester.
Q.7 Ortho-sulphobenzimide is used in the preparation of sweet for a diabetic person or patient, why ?
Q.8 How does prevailing temperature influence the extent of adsorption of a gas on solid.
Q.9 What do you mean by activity and selectivity of catalysts?
Q.10 What are the units of molar conductivity?
Q.11 Mention the factors which affect the rate of a chemical reaction.
Q.12 How will you convert –1. Toluene to benzyl alcohol 2. But –1-ene to But -2-ene.
Q.13 Give IUPAC names of following
OCH2 COOH
[1] [2] CI3 – C – CH2 Cl
O
Q.14 Halo arenes are less reactive towards electrophile than benzene.