12th Chemistry Paper Solutions Set 1 : CBSE Delhi Previous Year 2004

General Instructions:
(i) All questions are compulsory.
(ii) This question paper consists of four sections A, B, C and D. 
Section A contains 8 questions of one mark each.
Section B is of 10 questions of two marks each.
Section C is of 9 questions of three marks each and
Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
Q1 :

Mention a large scale use of the phenomenon called “reverse osmosis”™.


Answer :

Reverse osmosis is used on a large scale in the desalination of sea water.

Q2 :

Give an example of a pseudo first-order reaction.


Answer :

Inversion of cane sugar is a pseudo first-order reaction.

Q3 :

Mention two properties of acetonitrile because of which it acts as a good solvent.


Answer :

Two properties of acetonitrile because of which it acts as a good solvent are −

(i) Due to its high polar nature, it can dissolve variety of solvents.

(ii) It does not react with mild acidic and basic substances.

Q4 :

What are the types of lattice imperfections found in crystals?


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Q5 :

What is the principal ore of Iron?


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Q6 :

Write the chemical reaction to transform butanal to butanoic acid.


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Q7 :

Name the type of structure possessed by a unit cell of CsCl.


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Q8 :

Writethe IUPAC name of the following compound:


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Q9 :

Explain Brownian movement.


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Q10 :

Distinguish between reaction rate and reaction rate constant (specific reaction rate) of a reaction.


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Q11 :

Write the cell reactions which occur in lead storage battery (i) when the battery is in use and (ii) when the battery is on charging.


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Q12 :

Give chemical reaction in support of each of the following statements:

(i) The +1 oxidation state gets stabilised progressively from Ga to Ti in Group 13.

(ii) All the bonds in PCl5 molecule are not equivalent.


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Q13 :

Expand DDT. Write its structure.


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Q14 :

Write the names of reagents and equations in the conversion of

(i) phenol to salicyl aldehyde

(ii) anisole to p-methoxyacetophenone


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Q15 :

Write the modes of free-radical polymerisation of an alkene.

OR

Differentiate between addition and condensation polymers based on the mode of polymerisation. Give one example of each type.


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Q16 :

Differentiate between Lanthanides and Actinides series.


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Q17 :

Calculate the density of silver which crystallises in the face-centred cubic structure. The distance between the nearest silver atoms in this structure is 287 pm.


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Q18 :

Two elements A and B form compounds having formula AB2and AB4. When dissolved in 20 g of benzene (C6H6), 1 g of AB2lowers the freezing point by 2.3 Kwhereas 1.0 g of AB4lowers it by 1.3 K. The molar depression constant for benzene is 5.1 Kkg mol−1. Calculate atomic masses of A and B.


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Q19 :

Explain the Froth Floatation Method.


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Q20 :

Conductivity of 0.00241 M acetic acid is 7.896 x 10-5S cm-1. Calculate its molar conductivity and if for acetic acid is 390.5 S cm2mol-1, what is its dissociation constant?


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Q21 :

A reaction is first order in A and second order in B.

(i) Write differential rate equation.

(ii) How is the rate affected if the concentration of B is tripled?

(iii) How is the rate affected when the concentrations of both A and B are doubled?

What is the significance of rate constant in the rate expression?


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Q22 :

How are the colloids classified on the basis of the nature of interaction between dispersed phase and dispersion medium? Describe an important characteristic of each class. Which of these sols need stabilising agents for preservation?

Or

What are detergents? Give their scheme of classification. Why are the detergents preferred over soaps?


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Q23 :

Draw a figure to show splitting of degenerate dorbitals in an octahedral crystal field. How does the magnitude of Δ0 decide the actual configuration of dorbitals in a complex entity?


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Q24 :

Explain the following terms with suitable examples:

(i) Frenkel defect

(ii) Interstitials


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Q25 :

Draw the structures of monomers for the following polymers. Also draw the structures of the polymers and uses of:

(i) Teflon

(ii) PMMA

(iii) Buna-S


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Q26 :

(a) Identify A and B in the following:

(i)

(ii)


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Q27 :

Write the IUPAC names of the following:

(i)

(ii)

(iii)


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Q28 :

(a) Assign appropriate reason for each of the following observations:

(i) Anhydrous AlCl3is used as a catalyst.

(ii) Phosphinic acid behaves as a monoprotic acid.

(iii) SF6is not easily hydrolysed whereas SF4is readily hydrolysed.

(iv) No form of elemental silicon is comparable to graphite.

(b) Draw the structure of XeOF4 or BrF3.

Or

Account for the following:

(i) Ammonia is a stronger base than phosphine

(ii) The tendency to exhibit +2 oxidation state increases with increasing atomic number in group 14.

(iii) HF is a weaker acid than HI.


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Q29 :

(a) How would you account for the following:

(i) The transition elements exhibit high enthalpies of atomisation.

(ii) The 4dand 5dseries of the transition metals have more frequent metal−metal bonding in their compounds than do the 3dmetals.

(iii) There is a greater range of oxidation states among the actinoids than among the lanthanoids.

(b) Write the complete chemical equation for each of the following:

(i) An alkaline solution of KMnO4reacts with an iodide.

(ii) An excess of SnCl2solution is added to a solution of mercury (II)

Or

An aqueous solution freezes at 272.4 K, while pure water freezes at 273.0 K. Determine

(i) the molality of the solution

(ii) the boiling point of the solution

(iii) the lowering of vapour pressure of water at 298 K

[Given Kf= 1.86 K kg mol−1, Kb= 0.512 K kg mol−1and vapour pressure of water at 298 K = 23.756 mm Hg]


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Q30 :

Name the products obtained on complete hydrolysis of DNA. Enumerate the structural differences between DNA and RNA. In what way is a nucleotide different from a nucleoside? Illustrate with examples.

Or

Define and classify vitamins. Name the diseases caused due to lack of any three of them.


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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.