CBSE Board Class 11 Chemistry Previous Year Question Papers 2007

General Instructions:  General Instructions:
1. All questions are compulsory. 
2. Marks for each question are indicated against it. 
3. Question numbers 1 to 5  are very short-answer questions, carrying 1  mark each.  11
Answer these in one word or about one sentence each. 
4. Question numbers 6 to 12 are short-answer questions, carrying 2 marks each.  22
Answer these in about 30 words each. 
5. Question numbers 13 to 24  are short-answer questions of 3  marks each. Answer  33
these in about 40 words each. 
6. Question numbers 25 to 27 are long-answer questions of 5  marks each. Answer  55
these in about 70 words each. 
7. Use Log Tables, if necessary Use of calculators is not permitted. 

CHEMISTRY 2007

Q1. . How many atoms can be assigned to its unit cell i . .  f an element forms (i) body centred cubic
cell, and (ii) a face centred cubic cell?        

Q2. . What would be the value of Van't Hoff factor for  . .  a dilute solution of K 2 SO4 in water? 
          
Q3. . Express the relation between the half-life period . .  of a reactant and its initial concentration
for a reaction of nth
order.           

Q4. . Mention a chemical property in which methanoic ac . .  id differs from acetic acid. 

Q5. . How is the basic strength of aromatic amines affe . .  cted by the presence of an electron
releasing group on the benzene ring?       

Q6. . State that de Broglie relationship. How do de Bro . .  glie waves of a moving particle differ from
electromagnetic waves?          
Or  Show that the uncertainty principle is of little significance for an object of mass

Q7. . Predict the products of electrolysis obtained at  . .  the electrodes in each case when the
electrodes used are of platinum:        
(i) An aqueous solution of
(ii) An aqueous solution of

Q8. . State the basic reason of each of the following s . .  tatements:  
(i) In CI undergoes disproportionate reaction but TICI does not. 
(ii) AICI3 acts as a Lewis acid. 

Q9. . Write chemical equations for the following reacti . .  ons:   
(i) Ca3 (PO4 )2 +SiO2 +C –> 
(ii) XeF6 +H2O –> 

Q10. . Identify and mark the presence of centres of chir . .  ality’s, if any, in the following molecules.
Mention the number of stereoisomer possible in each case.    
(i) H3C - CH - CH 2 - CH - CH3
                  |                      | 
                OH                  OH 
   

Q11. . Explain how an OH group attached to a carbon in t . .  he benzene ring activates benzene
towards electrophilic substitution.       

Q12. . How are polymers classified on the basis of force . .  s operating between their molecules?
To which, of these classes does nylon-66 belong?     

Q13. . (a) Use the LCAO method for the formation of mole . .  cular orbitals in case of homonuclear
diatomic hydrogen molecule. 
(b) Which of the following has higher bond dissociation energy and why? 

Or 
What kinds of molecular forces exist between the species in the following pairs of particles and
why? 
(i) He and N2 
(ii) Cl2 and NO
(iii) NH3 and CO 

Q14. . Aluminum crystallizes in a face centred cubic clo . .  se-packed structure its atomic radius is
125 x 10-12m. 
(a) What is the length of the edge of the unit cell? 
(b) How many such unit cells are there in a 1.00 m piece of aluminium?  

Q15. . State Henry's law for solubility of a gas in a li . .  quid Explain the significance of Henry's law
constant ( At the same temperature, hydrogen Is more soluble in water than helium. Which of
them will have a higher value of KH and why?        

Q16. . The activation energy of a reaction is 75.2 kJ mo . .  r-1in the absence of a catalyst and50.14 kJ mol-1
with a catalyst. How many times will the rate of reaction grow in the presence of
the catalyst if the reaction proceeds at 250C? (R=8.3I4 JK-1mol-1) 

Q17. . How do size of particles of adsorbent, pressure o . .  f gas and prevailing temperature
influence the extent of adsorption of a gas on a solid?      

18.. (a) Write the structural formula of hex-2-en-4yno .. ic acid. 
(b) To illustrate the following reactions write one chemical equation for each: 
(i) Cross aldol condensation 
(ii) Hofmann bromamide reaction        

Q19. . Write the chemical reaction equation stating the  . .  reaction conditions required for each of
the following conversions:        
(i) Methyl bromide to ethylamine 
(ii) Aniline to phenol 
(iii) ptoluidine to 2-bromo-4-methylanilline 

Q20. . (a) Write the corresponding chemical reaction equ . .  ation to show that 
(i) PbO2 can act as an oxidizing agent. 
(ii) All the bonds in a molecule of PCI5 are not equivalent. 

(b) Write the structural formula for either XeF2 or IF3.    

Q21. . Draw a sketch to show the splitting of d-orbital  . .  in an octahedral crystal field. State clearly
how the actual configuration in split d-orbital in an octahedral crystal field is decided by the
magnitudes of  and P values.         

Q22. . The E° values at 298 K corresponding to the follo . .  wing two reduction electrode processes
are: 
(i) Cu+
/Cu=+0.52 V 
(ii) Cu2
+/Cu+=+0.16 V 
Formulate the galvanic cell for their combination. What will be the cell potential? 
Calculate the  for the cell reaction. (F=96500 C mol
-1
)    

Q23. . The radioactive isotope  . .  Co, can be made by an  or an  nuclear reaction.
State the appropriate target nucleus for each reaction. If the half-life of  Co is 7 years, how
long will it take for complete annihilation and why?    

Q24. . Describe the following with an example each:      .
(i) Antimicrobials 
(ii) Acid dyes 
(iii) Antioxidants 

Q25. . (a) The standard Gibbs energy change values  . .  at 1773 K are given for the
following reactions: 
4 Fe+3 O2 –> 2 Fe2 O3 ;  G0
=-1487 kj mol
-1
 
4 Al+3 O2 –> 2 Al2 O3 ;  G0
=-22500 kj mol
-1
 
2 CO+O2 –> 2 CO2 '  G0
=-515 kj mol
-1
 
Find out the possibility of reducing Fe2O3 and Al2O3 with CO at this temperature.  (b) Comment on the following statements giving reasons: 
(i) An exothermic reaction is sometimes not spontaneous. 
(ii) Reactions with  G0
values less than zero always have equilibrium constants greater than
1.            
Or 

(a) The half-reactions are: 
(i) Fe3++ e--–> Fe2+, E0= 0.76 V 
(ii) Ag++ e--–> Ag, E0= 0.80 V 
Calculate Kc for the following reaction at 25° C: 
Ag++ Fe2+–> Fe3++Ag (F=96500 C mol-1) 
(b) Define the following terms: 
(i) Isothermal and Adiabatic processes 
(ii) State variables / State functions 

Q26. . (a) Given below are the electrode potential value . .  s, E° for some of the first row of
transition elements: 
Element –>E0M2+/M (v)=
Explain the irregularities in these values on the basis of electronic structures of atoms. 
(b) Complete the following reaction equations:      
•  Cr2O  +Sn2+ + H+–> •  MnO  + Fe2++ H+–>
Or
(a) How would you account for the following: 
(i) Cobalt (II) is stable in aqueous solution. but in the presence of complexing reagents it is
easily oxidized. 
(ii) The transition elements exhibit high enthalpy of atomization. 
(iii) Of the d4 species, Cr2+ is strongly reducing while Mn ( Ill ) is strongly oxidizing. 
(b) Name the chief ore of copper and write the reactions Involved in its extraction from that ore. 
Q27. . (a) Write the chemical reactions of glucose with  . .  (i) NH2 OH and (ii) (CH3 CO)2 o. Also
draw simple Fischer projections of D-glucose and L-glucose. 
(b) Name the food sources and the deficiency diseases caused due to lack of any two of
vitamins A, C, E and K.         
Or 
(a) State the composition and functional differences between DNA and RNA. 
Describe the mechanism of replication of DNA. 
(b) Define 'mutation'.          3, 2  3, 2