Sunday 11 January 2015

                                                          SET CODE 011
                                 QUESTION PAPER CHEMISTRY (043)                                         CLASS- XII - (2014-15)         
 Time Allowed : 1.30 hrs                              Maximum Marks :29  

Ø  Use log tables if necessary, use of calculators is not allowed. 

Q1.Gelatin which is a peptide is added in ice creams. What can be its role. (1)

Q2. Write the formula for the coordination compound Tetra ammine diaqua cobalt (III) chloride.                                                                                                   (1)

Q3. A reaction is second order with respect to a reactant. How is the rate of the reaction affected if the concentration of the reactant is   i) doubled  ii) reduced to ½                                                                                                                         (2)

                                           OR

 A first order reaction is 15% complete in 20 minutes. How long it take to be 60% complete.

Q4. (a)  What is the relationship between standard free energy change and equilibrium constant.                                                                          (1)

b)  The standard emf of the cell    Zn(s) + Cu2+ (aq)  --> Zn2+(aq) + Cu (s) is 1.10v.   Calculate the standard Gibbs free energy change.(1)

Q5. Explain how (Pt Cl2 (NH3)2) and (Pt (NH3)6] Cl4 differ in their electrical conductances.                                                                     (2)

Q6. Calculate the packing efficiency in bcc structure.                                 (2)

 Q7 Determine the type of cubic lattice to which a given crystal belongs if it has edge length of 290 pm and density is 7.80 g cm-3 (molecular mass= 56 g mol-1).                                                                                                                    (3)

Q8. The decomposition of NH3 on platinum surface is zero order reaction. i)What are the rates of production of N2 and H2 if K = 2.5 ×10-4 mol-1LS-1. (2)

Q9.Account for the following  (i) A delta is formed at the point where the river water enters the sea.  (ii) Direct current is passed through a colloidal solution.  (iii) Ferric hydroxide sol is positively charged. (3)

Q10. Santosh and his mother went to a shop to purchase a battery for their inverter. Shop keeper showed them two types of batteries one with Cadmium plates and other with lead plates. The battery with cadmium plates was more expensive than the lead battery. Santosh's mother wanted to purchase lead battery as it was cheaper.  After reading above passage answer the following questions.                                                                                                                                  (a) As a students of chemistry, why would you suggest to santosh's mother to buy the expensive cadmium plate battery. Give two reasons.             (2)

 (b) What are the values associated with the above decision.              (1)

Q11 (a) What is the role of depressant in froth floatation process.      (1)

 (b) Describe a method or refining of nickel.                                           (2)

Q12.State Henry's law and mention its two applications.                        ( 2)

 (b) Which of the following has higher boiling point and why.   0.1M NaCl or 0.1 M Glucose                                                                (1)

(c) On dissolving 19.5 g of CH2FCOOH in 500 g of water a depression of 10C in freezing point of water is observed. Calculate the Vant Hoff factor. Given Kf = 1.86 K Kg mol-1.      (2)

                                                          OR

(a) State Raoult's  law for the solutions containing nonvolatile solute. Give its mathematical expression also.                              (2)                                                             
 
 (b) A solution containing 0.5 g of  KCl dissolved in 100 gm of water freezes at       -0.240C.                (2)                                                                                                                             
c) Calculate the degree of dissociation of the salt (K for water = 1.860C).    (1)
 
 
 
NOTE The answer keys for code o11 will be uploaded after 13 night so please check your answers and evaluate accordingly
 

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