12th Chemistry Paper Solutions Set 1 : CBSE Delhi Previous Year 2011

General Instructions:
(i) All questions are compulsory
(ii) Question numbers 1 to 8 are very short-answer questions and carry 1 mark each.
(iii) Question numbers 9 to 18 are short-answer questions and carry 2 marks each.
(iv) Question numbers 19 to 27 are also short-answer questions and carry 3 marks.
(v) Question numbers 28 to 30 are long-answer questions and carry 5 marks each.
(vi) Use Log Tables, if necessary. Use of calculators is not allowed.
Q1 :

Crystalline solids are anisotropic in nature”™. What does this statement mean?


Answer :

This statement means that some of the physical properties of crystalline solids such as electrical resistance or refractive index show different values when measured along different directions in the same crystals.

Q2 :

Express the relation between conductivity and molar conductivity of a solution held in a cell.


Answer :

The molar conductivity of a solution at a given concentration is related to conductivity of that solution, by the following relation. 

where, Λm is molar conductivity and is the conductivity of the solution.

Q3 :

Define “electrophoresis”™.


Answer :

Electrophoresis is the phenomenon of movement of colloidal particles under the applied electric potential.

Q4 :

Draw the structure of XeF2 molecule. 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q5 :

Write the IUPAC name of the following compound: 

(CH3)3 CCH2Br


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q6 :

Draw the structure of 3-methylbutanal.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q7 :

Arrange the following compounds in an increasing order of their solubility in water: 

C6H5NH2, (C2H5)2NH, C2H5NH2


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q8 :

What are biodegradable polymers?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q9 :

The chemistry of corrosion of iron is essentially an electrochemical phenomenon. Explain the reactions occurring during the corrosion of iron in the atmosphere.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q10 :

Determine the values of equilibrium constant (KC) and ΔG° for the following reaction: 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q11 :

Distinguish between “rate expression”™ and “rate constant”™ of a reaction.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q12 :

State reasons for each of the following: 

(i) The N − O bond in is shorter than the N − O bond in

(ii) SF6 is kinetically an inert substance. 

OR

State reasons for each of the following: 

(i) All the P-Cl bonds in PCl5 molecule are not equivalent. 

(ii) Sulphur has greater tendency for catenation than oxygen.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q13 :

Assign reasons for the following: 

(i) Copper (I) ion is not known in aqueous solution. 

(ii) Actinoids exhibit greater range of oxidation states than Lanthanoids. 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q14 :

Explain the following giving one example for each: 

(i) Reimer-Tiemann reaction. 

(ii) Friedel Craft”™s acetylation of anisole.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q15 :

How would you obtain 

(i) Picric acid (2, 4, 6-trinitrophenol) from phenol, 

(ii) 2-Methylpropene from 2-methylpropanol? 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q16 :

What is essentially the difference between α-form of glucose and β-form of glucose? Explain.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q17 :

Describe what you understand by primary structure and secondary structure of proteins.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q18 :

Mention two important uses of each of the following:

(i)Bakelite

(ii)Nylon 6


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q19 :

Silver crystallizes in face-centred cubic unit cell. Each side of this unit cell has a length of 400 pm. Calculate the radius of the silver atom. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. That is each face atom is touching the four corner atoms.) 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q20 :

Nitrogen pentoxide decomposes according to equation: 2N2O5(g) 4NO2(g) + O2(g) 

This first order reaction was allowed to proceed at 40° C and the data below were collected:

[N2O5] (M) Time (min)
0.400 0.00
0.289 20.0
0.209 40.0
0.151 60.0
0.109 80.0

(a) Calculate the rate constant. Include units with your answer. 

(b) What will be the concentration of N2O5 after 100 minutes? 

(c) Calculate the initial rate of reaction.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q21 :

Explain how the phenomenon of adsorption finds application in each of the following processes:

(i) Production of vacuum

(ii) Heterogeneous catalysis

(iii)Froth Floatation process

OR

Define each of the following terms:

(i) Micelles

(ii)Peptization

(iii)Desorption


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q22 :

Describe the principle behind each of the following processes:

(i)Vapour phase refining of a metal.

(ii)Electrolytic refining of a metal.

(iii)Recovery of silver after silver ore was leached with NaCN.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q23 :

Complete the following chemical equations:

(i)

(ii)

(iii)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q24 :

Write the name, stereochemistry and magnetic behaviour of the following: 

(At. nos. Mn = 25, Co = 27, Ni = 28) 

(i) K4[Mn(CN)6

(ii) [Co(NH3)5Cl]Cl2

(iii) K2[Ni(CN)4]


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q25 :

Answer the following: 

(i) Haloalkanes easily dissolve in organic solvents, why? 

(ii) What is known as a racemic mixture? Give an example. 

(iii) Of the two bromoderivatives, C6H5CH(CH3)Br and C6H5CH(C6H5)Br, which one is more reactive in substitution reaction and why? 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q26 :

(a) Explain why an alkyl-amine is more basic than ammonia. 

(b) How would you convert 

(i) Aniline to nitrobenzene 

(ii) Aniline to iodobenzene? 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q27 :

Describe the following giving one example for each: 

(i) Detergents 

(ii) Food preservatives 

(iii) Antacids 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q28 :

(a) Differentiate between molarity and molality for a solution. How does a change in temperature influence their values? 

(b) Calculate the freezing point of an aqueous solution containing 10.50 g of MgBr2 in 200 g of water. (Molar mass of MgBr2 = 184 g) (Kf for water = 1.86 K kg mol−1

OR

(a) Define the terms osmosis and osmotic pressure. Is the osmotic pressure of a solution a colligative property? Explain. 

(b) Calculate the boiling point of a solution prepared by adding 15.00 g of NaCl to 250.0 g of water. (Kb for water = 0.512 K kg mol−1), (Molar mass of NaCl = 58.44 g)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q29 :

(a) Give chemical tests to distinguish between 

(i) Propanal and propanone, 

(ii) Benzaldehyde and acetophenone. 

(b) How would you obtain 

(i) But-2-enal from ethanal, 

(ii) Butanoic acid from butanol, 

(iii) Benzoic acid from ethylbenzene? 

OR

(a) Describe the following giving linked chemical equations: 

(i) Cannizzaro reaction 

(ii) Decarboxylation 

(b) Complete the following chemical equations: 

(i) 

(ii) 

(iii)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q30 :

(a) Explain the following: 

(i) NF3 is an exothermic compound whereas NCl3 is not. 

(ii) F2 is most reactive of all the four common halogens. 

(b) Complete the following chemical equations: 

(i) C + H2SO4 (conc)

(ii) P4 + NaOH + H2O

(iii)

OR

(a) Account for the following: 

(i) The acidic strength decreases in the order HCl > H2S > PH3

(ii) Tendency to form pentahalides decreases down the group in group 15 of the periodic table. 

(b) Complete the following chemical equations: 

(i) P4 + SO2Cl2

(ii) XeF2 + H2O

(iii)


Answer :

Please Register/Login to get access to all solutions Facebook Login

12th Chemistry Paper Solutions Set 3 : CBSE Delhi Previous Year 2013 will be available online in PDF book soon. The solutions are absolutely Free. Soon you will be able to download the solutions.