KV-3,AFS,Bhisiana

Sample Paper (Half Yearly)

Class –XII(Chemistry)-2008-2009

Time : 3Hrs MM:70

General instruction

1. All Questions are compulsory2. Q.No-1-8 are very short answer questions & carry 1 marks each3. Q.No- 9-18 are of short answer questions & carry 2 marks each4. Q.No 19-27 are of short answer questions & carry 3 marks each.5. Q .No 28-30 are long answer questions & carry 5 marks each.6. Use of calculator is not allowed use log tables if necessary.

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Q:1 What do you mean by activity & selectivity of catalysts.?

Q:2 Give IUPAC name for the coordination isomer of [Co(NH3)6][Cr(CN)6].

Q:3 What are ambident nucleophiles ? Give one example.

Q:4 Give a simple test to distinguish between propanal & propanone.

Q :5 Arrange the following in decreasing order of their basic strength:

C6H5NH2,C2H5NH2,(C2H5)2NH,NH3

Q:6 Why cannot Vitamin C be stored in our body ?.

Q: 7 Define thermoplastic & thermosetting polymers.

Q:8 What is meant by the term chemotherapy?

Q:9 An element has body centred cubic structure with a cell edge of 288 pm .The density of the element is 7.2 g/cm3 .How many atoms are present in 208 g of the element.?

Or

Analysis shows the nickel oxide has the formula NiO0.98 O1.00 .What fractions of nickel exist as NI+2 & NI+3 ions.

Q10 (a) Differenciate between schottky & Frenkel defects (any 2 differences)

(b) A cubic solid is made of two elements P & Q Atoms , ‘Q’ are at the corners of the cube & ‘P’ at the body centre.what is the formula of the compound .?

Q:11 (a) What is expected Vant hoff factor for K4[Fe(CN)6]?.

(b) What are minimum boiling azeotropes? Give one example.

Q:12 Why is Cr+2 reducing & Mn +3 oxidizing when both have d4 configuration.?

Q:13 Write the names & structures of the monomers of the following polymers :

(i) Buna-S (ii) Neoprene

Q:14 Calculate the equilibrium constant of the reaction.

Cu(s) +2 Ag+(aq) -> Cu+2(aq) +2 Ag(s)

E0cell =0.46 v.

Q:15. Differentiate between SN1 & SN2 mechanism by taking suitable example.

Q:16 How do antiseptics differs from disinfectants.? Give one Example of each.

Q:17 Explain why

(a) Alkyl halides are insoluble in water?(b) Grignard reagent should be prepared under anhydrous conditions?

Or

The treatment of alkyl halides with aqueous KOH leads to the formation of alcohols but in presence of alcoholic KOH ,alkenes are major products explain.

Q:18 What is crystal field splitting energy ? How does the magnitude of ∆0 decide the actual configuration of d-orbitals in a co-ordination entity?

Q:19 Conc.nitric acid used in laboratory work is 68% nitric acid by mass in aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 1.504 g/ml.

Or

The boiling point of benzene is 353.23 k. When 1.80 g of a non volatile solute was dissolved in 90g of benzene ,the boiling point is raised to 354.11 K calculate the molar mass of solute (Kb for benzene is 2.53 k kg /mol) .

Q:20 (a) How much electricity is required in coulomb for the oxidation of

(i) 1 mol of H2O to O2

(ii) 1 mol of FeO to Fe2O3.

(b) Define the term specific conductance & molar conductivity for solutions of electrolytes.

Q:21 (a)Bond angle in PH4+ is higher than that in PH3 Why?.

(b) Why does PCl3 fume in moisture ?.

(c) Why is H2O a liquid and H2S a gas.

Q:22 Describe the oxidizing action of K2Cr2O7 & write the ionic equations for its reaction with .

(i) Iodide (ii) Iron(II) sulphate & (iii) H2S.

Q:23 Explain the following with an example

(i) Reimer-Tiemann reaction.(ii) Williamson synthesis of ethers.

Q:24 (a)What are essential and non essential amino acids . Give example also

(b)What are enzymes ?

(c)What do you understand by term glycosidic linkage ?

Q 25.Account for the following

(i)PKb of aniline is more than that of methylamine

(ii)aniline does not undergo Friedel-crafts reactions.

iii) Ethylamine is soluble in water where as aniline is not.

26) What is an adsorption isotherm ? Describe Freundlich adsorption isotherm?

27) (a) Although thermodynamically feasible in practice , magnesium metal is not used for the reduction of alumina in the metallurgy of aluminum.why?

(b) Out of C & CO, which is a better reducing agent at 673k?

(c) Outline the principle of vapour phase refining.

28)(a) An organic compound with the molecular formula C9H10O forms 2,4- DNP derivative reduces Tollen’s reagent & undergoes Cannizzaro’s reaction .On vigorous oxidation it gives 1,2-benzenedicarboxylic and identify the compound.

(b) Give reason:

There are two –NH2 groups in semicarbazide . However only one is involved in the formation of semicarbazones.

OR

28) An organic compound (A) with the molecular formula C8H16O2 was hydrolysed with dilute H2SO4 to give a carboxylic acid (B) and alcohol (C). Oxidation of (C) with chromic acid are produced (B) , (C )on dehydration gives but- 1-ene.write equation for the reactions involved.

29) How is Ozone estimated quantitatively ? explain .

(b) Write the balanced chemical equation for the reaction of Cl2 with hot & concentrated NaOH .Is this reaction a disproportionation reaction ?justify.

(c) How are XeO3 and XeOF4 prepared ?.

OR

29) Arrange the following in the order of property indicated for each set:

i) F2, Cl2, Br2,I2 (increasing bond dissociation enthalpy)

ii) HF, HCl, HBr, HI (increasing acid strength)

iii) NH3 , PH3, AsH3, SbH3, BiH3(increasing base strength)

iv) NH3 , PH3, AsH3, SbH3, BiH3 (increasing bond angle)

v) H2O, H2S, H2Se , H2Te (increasing thermal stability)

30)(a) The activation of energy for the reaction:

2HI → H2 + I2

(g) (g)

is 209.5kj/mol at 581K,Calculate fraction of molecules of reactant having energy equal to or greater than activation energy .

(b) The rate of reaction X→ Y becomes 8 times when the conc. of the reactant X is doubled .Write the rate law of reaction .

OR

30)(a) The rate constant for a first order reaction is 6s-1 .How much time will it take to reduced the initial conc. of reactant to its 1/16th value?.

(b)Wwhat are pseudo first order reaction?Give one example.

(c)Differentiate between order and molecularity?