Saturday, April 12, 2014

What is denoted by ln?

Question: What is denoted by ln?

Answer: ln is the symbol of natural log. Log is modern symbol.

ln = 2.303 log

Sample paper

General Instructions
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. Find out the number of atoms per unit cell in a fcc structure having only single
    atoms at its lattice points .                                                                                                                                                                    
2. State the condition resulting in reverse osmosis.                                                                                                        
3. Express the rate of the following reaction in terms of disappearance of hydrogen in the reaction  
     N2 +3H2  ---------->  2NH3     .                                                                                                                     
4. Define molar conductivity for the solution of an electrolyte.                                                                                 
5. PbO2  is a stronger oxidizing agent than SnO2 .                                                                                                                                                                    
6. Why the transition metals generally form colored compounds ?                                                                        
7. Which out of the following are transition element and why?  Zn, Ag, Cd, Au                                                
8. Why is the separation of lanthanide elements  difficult ?                                                                                       
9. Assign reasons for the following    
(i) Phosphorus doped silicon is a semiconductor .
(ii) Schottky defect lowers the density of a solid .                                                                          
10. An element has a body centered cubic  structure with a cell edge of 288 pm.The density
 Of the element is 7.2 g/cm3.Calculate the no. of unit cells in 208 g of the element.                                         
11. Explain the following:
        1.F –centre    2.A hole                                                                                                                                                                                     
12. A 0.1539 molal aqueous solution of cane sugar (mol. Mass = 342 g/mol) has a freezing point                 
 of 271 K While the freezing point of pure water is 273.15 K. What will be the freezing point of
 an aqueous solution Containing 5 g of glucose (mol. Mass =180 g/mole) per 100 g of solution?                 
13. Calculate the standard cell potential of the galvanic cell in which the following reaction takes place
  2 Cr +3 Cd +2  ---------->2 Cr +3   +3 Cd
 Given E0Cr +3 /Cr =0.74 V   , E0Cd +2 /Cd = -0.40 V and F =96500C/mol                                                    
14. Explain the following terms with a suitable example in each case:                                                 
(i) Shape- selective catalysis
15. (i) What is the role of graphite rod in the electrometallurgy?
(ii) Write the principle of zone refining method.                                                                                                            
16. What is dis -proportionation reaction? Write a chemical reaction to show disproportionation.             
17. What is meant by actenoid contraction? Discuss the important physical properties  of  
18. Using valence bond theory predict the shape and magnetic behavior  of [Cr(NH3)6]3+ion.                          
 19. Consider a plot between k vs  where T is the temperature. 
 On the basis of  this plot, answer the following questions 
                 (i)        What is the slope in this line ?
                (ii)         What is the intercept of this line on the y-axis ?
               (iii)         Which area of kinetics is shown by the plot?                                                                            
20. A certain reaction is 50% complete in 20 minutes at 300K and the same reaction is again 50%
     complete in 5 minutes at 350K.Calculate the activation energy if it is a first order reaction.
     Given R=8.314 J/K/mol                                                                                                                                           
21. Describe briefly :
    1. Hardy-Schulze rule
   2.  Peptization
   3.  Electrophoresis                                                                                                                                                     
22. Why is zinc not extracted from zinc oxide through reduction using CO? Give the name of any ore of zinc.                                                                                                                                                                                           
23. Assign a reason for each of the following statements;
1. Phosphinic acid behave as a mono protic acid .
2. More metal fluorides are ionic in nature than metal chlorides
3. Iodine forms I3- ion but F2 does not form F3-ion.                                                                                                 
24. Complete and balance the following equations :
     1. C2H4 +O2 ---------->
      2. 4Al +3O2 ----------->
      3. P4 +SO2Cl2----------->                                                                                                                                                                                 
25. Draw the structures of the following compounds :
     (i) SF4
    (ii) XeF2
   (iii) N2O5                                                                                                                                                                                                                                                                                     
26. Why (I ) Transition metal and their many compounds act as good catalyst.
  (ii) Actinoid contraction is greater from element to element than lanthanoid contraction.
 (iii) K2PtCl6 is a well known compound whereas corresponding Ni compound is not known.                    
27. Write the IUPAC name of [Co(NH3)5(NO2)]( NO3)2  and illustrate  the isomerism  exhibited by this
      Complex compound . Is the name of its isomer differ from this compound?.  
 a. Using Valence bond theory, predict the shape and magnetic character of [Ni(CO)4].[Ni=28]
      b. Give one example of application of coordination compounds in medicine.                                          
28. 1.Write the Nernst Equation and calculate the e.m.f  of the following cell at 298 K:
    Cu(s) / Cu2+(0.130M) II Ag+(1.00x10-4M) /Ag(s)
    Given E0   Cu2+ /Cu =+0.34 V and E0   Ag+ /Ag =+0.80 V.                                                                  
      2. Describe the preparation and electrode reactions of fuell cell .                                                               
      1. Explain Kohlrausch’s law of independent migration of ions. Write its one application.
      2. How conductivity of an unknown solution be determined? Explain 
29. Discuss the general characterstics of group 15 elements with reference to their :
   1. Electronic configuration   2.Oxidation states   3.Atomic size    
   4. Ionization enthalpy             5.Electronegativity                                                                                               
a. Complete and balance the following chemical equations:
 1. F2+H2O(cold)------------->
 2. BrO3- +F2+OH--------------->
  3. Ca3P2+ H2O------------->
b. Write the reaction for thermal decomposition of sodium azide.
c. Why does PCl3 fume in moisture?
30. a. Explain deviation from Raoult’s law in terms of molecular interactions.
b. Vapour pressure of pure water at 298 K is 23.8 mmHg.50 g of urea (NH2CO NH2) is dissolved in
      750 g of water .Calculate the vapour pressure of water for this solution and its relative lowering.      
a. Define the following terms :
       1. Mole fraction
       2. Van’t Hoff factor
      b. Calculate the freezing point of a solution containing 18 g of C6H12O6 and 68.4 g of C12H22O11

in 200 g water. The freezing point of pure water is00C and cryoscopic Constant of water is 1.86 K/m.            

Can PCl3 act as an oxidising as well as reducing agent? If yes, how? Illustrate with the help of equations.

Question: Can PCl3 act as an oxidising as well as reducing agent? If yes, how? Illustrate with the help of equations.
ANswer: Yes, PCl3 can act both as an oxidising agent as well as reducing agent.
It react with sulphur tri oxide to reduce it to sulphur di oxide.
PCl3 +SO3  -------------> POCl3 + SO2
It also react with metals like silver and sodium to form their chlorides.

PCl3 + 6 Na ---------------> 3 NaCl +Na3P

What inspired N.Bartlett for forming xenon compounds?

Question: What inspired N.Bartlett for forming xenon compounds?

 Answer: N.Bartlett observed that ionisation enthalpy of xenon is closer to oxygen and got inspired to form similar compound as he made with oxygen by PtF6 as O2PtF6.

What is the relation between butane and 2-methyl propane?

Question: What is the relation  between butane and 2-methyl propane?

Answer:Both are isomers.