CBSE Board Class 11 Chemistry Previous Year Question Papers 2008

Previous Paper 
Class 11

1. Define bonding molecular orbital.   

2. Define antibonding molecular orbital.   

3. Explain diagrammatically the formation of molecular orbital by LCAO.  

4.  Which one 2- 2 2 O and O , − may exhibit paramagnetism?  

5. Why are bonding molecular orbitals more stable than antibonding molecular
orbitals? 

6.  He 2 does not exist. Explain in terms of LCAO.   

7. Define bond order.   

8. Define hydrogen bonding   

9. What are the types of H-bonding? Which of them is stronger?  

10.  NH3has higher boiling point than  PH3. Give reason.   
                      
11. Define standard boiling point.  

12. What is surface energy?   

13. What is surface tension? What is its S.I unit?   

14. How does surface tension change when temperature is raised?  

15. Why does viscosity of liquids decrease as the temperature is raised?  

16. Why are tyres of automobiles inflated to lesser pressure, in summer than in
winter?  

17. Why is glycerol highly viscous?   

18. What is the effect of temperature on 
(i)   density 
(ii)   vapors pressure of a liquid?  

19. Some tiny light hollow spheres are placed in a flask. What  would happen to
these spheres, if temperature is raised? 

20. The boiling points of a liquid rises on increasing pressure. Give reason.  
  
21. Define spontaneous process.   

22. Define non-spontaneres process.   

23. What is the sign of enthalpy of formation of a highly stable compound?  

24. Predict the sign of  ∆S for the following reaction  CaCo3 (s)

25 2 CaO CO g( ). → +∆

26. Two ideal gases under same pressure and temperature are allowed to mix in
an isolated system – what will be sign of entropy change? 

27. Predict the sign of the entropy change for each of the following changes of
state. 
(a)     Hg l Hg g ( ) ( ) →
(b)AgNO S AgNO aq ( ) ( ) →
(c) I2(g)2 → I S( )
(d)C graphite C diamond ( ) ( ) →

28. Explain how is enthalpy related to spontaneity of a reaction?   

29.  The 2 2 ∆ ∆ → H g and S for 2Ag O(s) 4Ag(s) +O ( ) are given + 61.17kJ mol -1 and + 132 Jk-1mol -1 respectively. Above what temperature will the reaction be spontaneous?