CBSE Guess paper class XII Chemistry 2008 6


Guess Paper – 2008

Class – XII

Subject - Chemistry

NOTE: 1. Question No.1 to Question No. 8 carry one mark.Write answer in one word or

in one sentence.

2. Question No.9 to 18 carry two marks.Write answer in 20 to 30 words.

3. Question No.19 to 27 carry three marks.Write answer in 30 to 40 words.

4. question No.28 to 30 carry five marks. Write answer in 70 to 80 words.

1.Why is glass considered a super cooled liquid liquid?

.2.In a process adsorbate and adsorbent are held by strong force like a chemicalbond.Name the type of adsorption?

3.Why NH3 has higher boiling point than PH3 ?

4.Name the oxometal anion of the first series of the transition metal in which the metal exhibit same oxidation state equal to the group number?

5.Write IUPAC name of CH3 CH(Cl)CH(Br)CH3

6.Why CH3CHO is more reactive than CH3 CHO towards nucleophilic addition reaction?

7.Is –[CH2 -CH (C6 H 5) -]n a homopolymer or a copolymer?

8.Why do we require artificial sweeting agent?

9.N2 is bubbled through water at 293K .How many milli moles of N2 would dissolve in 1 lt of water.Assume that N2 exerts a partial pressure of .987 bar.Given that Henry’s law constant for N2 is 76.48 bar.

OR

18 gm glucose is dissolved in 1Kg of water .At what temperature will water boil at 1.013 bar. Kb for water is .52 KKg / mole.

10.The conversion of molecules X to Y follows second order kinetics.If concentration of X is increased to three times how will it affect the rate of formation of Y.?

11.Explain:

(a)Why elements of 3d series have irregular E 0 value?

(b)Which is a stronger reducing agent Cr ++ or Fe +++ ?

12.Explain

(a)Bi + act as strong oxidizing agent.

(b)Nitrogen do not from pentahalides

13.Explain Lanthanoid Contraction and its consequences?

14.Explain with one example (a) Carbylamine Reaction (b) Kolbe reaction

15.What happens when D- Glucose is treated with (a) HI (b) HNO 3

16.Define (a) Peptide Linkage (b) Primary Structure of protein

17.Write monomers of (a) Teflon (b) Bakelite

18. What are cationic detergents.Explain with one example?

19.Explain (a) Why o-nitrophenol has lower boiling point than p - nitrophenol?

(b) Give mechanism of the reaction when ethanol is heated with sulphuric acid at 443 K temperature.

20.Aluminium has cubic close packed structure its metallic radius is 125pm.

(a) What is the length of the side of the unit cell ?

(b) How many unit cells are there in 1cm3 of Al.?

21(a)Why do non ideal solution show negative deviation.Explain with an example?

(b)Why osmotic pressure is preffered to determine the molecular mass of macromolecule?

OR

(a)Why do abnormal values of molecular mass is obtained?

Explain?

(b)Define Raoult’s law for non volatile solute?

22.The following data were obtained during the first order decomposition of N2 O5 at constant volume.

2N2O5 -------à 2N2O4 + O2

S.N. TIME (sec) TOTAL PRESSURE (atom.)

1. 0 .5

2. 100 .512

Calculate rate constant.

23.Explain

(a) Colloid is not a substance but a state of substance.

(b)Why is adsorption always exothermic?

24. (a) How is cast iron different from pig iron?

(b) Explain Zone refining?

25(a) Write linkage isomer of [Co (NH3 )5 NO2 ] Cl 2

(b)Explain the splitting of d-orbital in a octahedral complex?

26.Explain

(a) Why preparation of chloroalkane by the action of SOCl2

On alcohol is preferred?

(b) Why is H2SO4 not used during the reaction of alcohol with KI.?

(c) Why p-isomer of dihalobenzene has M.P. 70o to 100 0

higher than ortho and meta isomer?

27.Find A,B,C,D,E and F

Benzene is heated with nitric acid and sulphuric acid to give A.Treatment of A with hydrochloric acid and Sn gives B.B is treated with nitrous acid and hydrochloric acid in a ice cold solution to give C. C is treated with CuCN to give D. D is treated with LiAlH4 to give E.C on treatment with F gives C6H5 N=N C6H5 OH

28.(a) Calculate E.M.F. of the cell:

Ni(s) + 2Ag+ (.002M) ----à Ni++ (.160M) + 2Ag(s)

Eocell=1.05V

(b) Explain the variation of molar conductivity of strong and weak electrolyte with dilution?

OR

(a) Molar conductivity of NaCl, HCl and NaAc are 126.4,425.9 and 91 S cm2 /mole calculate molar conductivity of HAc.

(b) Write anode and cathode reactions of a secondary cell,when charging and discharging is taking place by explaining lead storage battery

29.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 oxide is prepared.Draw its structure?

OR

(a) Why all the bonds in PCl5 are not of equal length?

(b) Why H2S is less acidic than H2Se ?

(c) How is O3 estimated quantitatively?

(d) Whf fluorine has lower electron gain enthalpy than chlorine?

(e) What inspired N.Bartlett for carrying out reaction betbeen Xe And PtF6 ?

30.(a) Give a chemical test to distinguish betbeen CH3CHO and CH3COCH3

(b)Convert:

(i) Benzaldehyde to benzoic acid

(ii) Benzoic acid to benzamide

(iii) 4- methyl acetophenone to benzenedicarboxylic acid

OR

(a) Give a chemical test to distinguish CH3COOH and C6H5COOH

(b) Convert:

(i) Acetaldehyde into 2-propanol

(ii) Toluene into benzaldehyde

(iii) Ethane into But-2enal

 

iCBSE India