Microsoft word - chemistry paper 1.doc

CHEMISTRY
PAPER – 1
(THEORY)
(Three Hours)
(Candidates are allowed additional 15 minutes for only reading the paper.
They must NOT start writing during this time.) --------------------------------------------------------------------------------------------------------------------- Answer all questions in Part I and six questions from Part II, choosing two questions
from Section A, two from Section B and two from Section C.
All working, including rough work, should be done on the same sheet as, and adjacent to, The intended marks for questions or parts of questions are given in brackets [ ]. Balanced equations must be given wherever possible and diagrams where they are helpful. When solving numerical problems, all essential working must be shown. In working out problems use the following data: Gas constant R = 1.987 cal deg-1 mol-1 = 8.314 JK-1 mol-1 = 0.0821 dm3 atm K-1mol-1 1 l atm = 1 dm3 atm = 101.3 J. 1 Farday = 96500 Coulombs. Avagadro’s number = 6.023 × 1023. --------------------------------------------------------------------------------------------------------------------- PART I (20 Marks)
Answer all questions.
Question 1
Fill in the blanks by choosing the appropriate word/words from those given in the (acetaldehyde, salt solution, 0.68, R, formaldehyde, buffer solution, 0.524, i, calcium
formate, 50 minutes, below, 45 minutes, 0.74, van’t Hoff factor, Raoult’s Law, weak,
strong, increases, decreases, positive, negative, above.)
The solution obtained by mixing appropriate amount of _______base and its salt with strong acid is called ________. An aqueous solution of glucose boils ______ 100oC and freezes ______ 0oC. (iii) The ratio of the observed value of a colligative property to the normal value of the same property is termed as ________ and is represented by letter _______. (iv) When a mixture of calcium acetate and _______ is subjected to dry distillation A _________ catalyst increases the rate of a chemical reaction while a negative catalyst _________ the rate of the reaction. Complete the following statements by selecting the correct alternative from the [5]
choices given:-
A saturated solution of Ag2CrO4 is 2×10-4 moles/litre. Its solubility product is: A molecule contains atoms x and y so that x occurs at the corners of the cube while y at the face centres. The formula of the molecule can be: (iii) 15 moles of hydrogen (H2) and 5.2 moles of iodine (I2) are mixed and allowed to attain equilibrium at 500oC. At equilibrium, the concentration of HI is found to be 10 moles. The equilibrium constant for the formation HI is: (iv) Glucose gives silver mirror test with Tollen’s reagent. It shows the presence of: In the formation of K4[Fe(CN)6], the hybridisation involved is: Why, Fe2+ has smaller radius than Mn2+ ? Write the Nernst equation for the following cell reaction: (iii) Draw the structure of isomers for molecular formula C3H6Cl2 which can exhibit (iv) What are the products formed when phenol and nitrobenzene are treated separately with a mixture of conc. sulphuric acid and conc.niric acid? How will you prepare 2-methyl propan – 2 ol from methyl magnesium bromide. Give balanced equations. PART II (50 Marks)
Answer six questions choosing two from Section A, two from
Section B and two from Section C.
SECTIO A
Answer any two questions.
Question 2
What is the molarity of a solution which freezes at -0.192oC assuming no change in [3]
the solute by raising the temperature, at what temperature will the same solution
boil? (Kf for water is 1⋅86oC kg mol-1 and Kb for water is 0⋅515oC kg mol-1) Phenol (M.W. = 94) associates in benzene to a certain extent to form dimer. A [2]
solution containing 20g of phenol in 1000 gms of benzene has its freezing point
decreased by 0⋅69 K. Calculate the observed molecular weight and the degree of
association of phenol. (Kf for benzene is 5⋅12 K kg mol-1).
If three elements P, Q and R crystallise in a cubic solid lattic with P atoms at the corners, [2]
Q atoms at the cube centre and R atoms at the centre of faces of the cube, then write the
State the Le Chatelier’s principle. What are the conditions for getting maximum yield of [3]
ammonia by Haber’s process?
Question 3
An element having bcc geometry has atomic mass 50. Calculate the density of unit [2]
cell, if its edge length is 290 pm.
What is the effect of dilution on the strength of weak acids? Explain. The following electrochemical cell is set up at 25oC: (iv) Is the reaction spontaneous or non-spontaneous? 2H2(g) + 2NO(g) ⇌ 2H2O(l) + N2(g) the following rate data was obtained. The order of reaction with respect to NO and H2 . Question 4
Define the terms specific conductance and equivalent conductance. What is the [2]
relationship between specific and equivalent conductance?
A solution containing 2 g of anhydrous barium chloride in 400 ml of water has a [3]
conductivity of 0⋅0058 ohm-1cm-1. Calculate the molar and equivalent
conductivities of this solution (at wt. Ba = 137, Cl = 35⋅5)
An aqueous solution of AlCl3 is acidic and that of Na2CO3 is basic. The hydrolysis of esters begins slowly but becomes fast after some time. (iii) The concentration of hydroxyl ions in aqueous ammonia decreases on the addition What is the effect of temperature on ionic product of water and why? What happens to [2]
the ionic product of water if some acid is added to it?
SECTIO B
Answer any two questions
Question 5
Write the IUPAC name of the following coordination compounds: What type of structural isomerism is exhibited by the following pairs of compounds: [Cr (H2O)5 Cl]Cl2⋅H2O and [Cr(H2O)4 Cl2]Cl⋅2H2O [Co Br (NH3)5]SO4 and [Co(SO4) ( NH3)5]Br (iii) [Cr (SCN) (H2O)5]2+ and [Cr (NCS) (H2O)5]2+ (iv) [Cu (NH3)4] [Pt Cl4] and [Pt (NH3)4] [Cu Cl4] K2 [Pt Cl4] is ionised to give three ions, when dissolved in water. Will it form white Question 6
Write the balanced chemical equations for the following: Sulphur dioxide gas is passed through acidified potassium permanganate solution. Potassium dichromate is treated with acidified ferrous sulphate solution. (iii) Silver nitrate is added to dilute solution of sodium thiosulphate. What is meant by Lanthanoid contraction? Write the general electronic configuration of [2]
inner transition elements.
Question 7
Sulphur dioxide acts both as an oxidising and a reducing agent. Give one reaction each [2]
to show its oxidising and reducing nature.
How will you obtain pure copper from its most important ore? Write all the steps and [3]
reactions involved in it.
Answer any two questions.
Question 8
(iv) Nitrobenzene to p-aminoazobenzene. Complete the following reactions and name the reactions. C6H5NH2 + _______ + KOH → C6H5NC + KBr + H2O Give one good chemical test to distinguish between the following pairs of compounds: Question 9
An aromatic compound ‘A’ on treatment with aqueous ammonia and heating forms compound ‘B’ which on heating with Br2 and KOH forms a compound ‘C’ of molecular formula C6H7N. Identify the compounds A, B and C. Give one example of a polyester and name the monomers from which it is formed. (ii) Write the monomers of the following polymers: Do the compounds having – C = N – and –N = N – bonds show geometrical isomerism? If yes, give one example of each and name the isomers. How can you chemically convert methylamine to ethylamine? Question 10
Give balanced equations for the following reactions: Benzoic acid is treated with phosphorous pentachloride. (iii) Aniline is heated with chloroform and alcoholic caustic potash. (iv) Benzoyl chloride is heated with hydrogen in the presence of palladium and barium Write three possible isomers having molecular formula C3H6O2. How will you distinguish between primary, secondary and tertiary aliphatic amines?

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