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M P Keshari » ISC GUESS PAPER IN CHEMISTRY FOR 2012.

ISC GUESS PAPER IN CHEMISTRY FOR 2012.

This item was filled under [ ISC ]

ISC Guess Paperin Chemistry for – 2012.

Chemistry

Time – 3 Hours. Full Marks – 70.

Part – I

(Answer all questions)

Q.1. (a) Correct the statement given below by changing the underlined part of the sentences :                                                                                                       [5]

(i) Water boils below 100º C when sodium chloride is added to it.

(ii) The rate constant of the first order reaction is directly proportional to the

concentration of reactant.

(iii) When acetone is treated with sodium chloride, a white precipitate is formed.

(iv) When dilute alkali is treated with acetaldehyde, it undergoes Cannizzaro’s

reaction.

(v) The formation of Chlorobenzene from benzene is a SN-Z-reaction.

(b) Complete the ststement given below by choosing the correct alternatives from the choices given below :                                                                                             [5]

(i) Mesotartaric acid is optically inactive because

(1) it has a double bond.

(2) it has no chiral carbon atom.

(3) of internal compensation.

(4) of external compensation.

(ii) The reaction between A and B is first order with respect to A and second order with respect to B. If the concentration of A is halved and that of B is doubled, the rate of reaction will be

(1) double the initial value.

(2) half the initial value.

(3) three times the initial value.

(4) same as the initial value.

(iii) Which one of the following  forms a chelate?

(1)   Acetate.

(2)   Oxalate.

(3)   Cyanide.

(4)   Ammonia.

(iv) By the condensation of hexamethylene diamine with adipic acid, the fibre obtained is :

(1)   Nylon 66.

(2)   Polyster.

(3)   Teflon.

(4)   Dacron.

(v) When zinc granule is dipped into copper sulphate solution, copper is precipitated from copper sulphate solution because :

(1) Reduction potential of copper is higher than that of zinc.

(2) Reduction potential of copper is lower than that of zinc.

(3) Both copper and zinc have a positive reduction potential.

(4) Both copper and zinc have negative reduction potential.

(c) Fill in the blanks by appropriate word/words from those given in the brackets : [5]

[formaldehyde, neutron, phenol, acetaldehyde, cyanohydrin, proton, independent, anode, tartaric acid, cathode, acetone, depends, methylcyanide, fission, first,  theoretical, mechanism, yellow, lactic acid, white, acetoxime, second, third.]

(i)                 Acetaldehyde reacts with HCN to give _________ which on hydrolysis gives _____________.

(ii)               A __________ precipitate is formed during addition of iodine and sodium hydroxide to ____________.

(iii)             Molecularity is a ____________ concept and its value is derived from the __________ reaction.

(iv)             The movement of electrons in the external circuit is from ___________ to __________ in a galvanic cell.

(d) Match the following :                                                                                            [5]

(a) Acetaldehyde                                            (i) Wohler Synthesis

(b) Homolytic fission                                      (ii) Ostwald’s Dilution Law

(c) Tollen’s reagent                                         (iii) Aldol

(d) Urea                                                           (iv) Free radical

(e) Weak electrolyte                                        (v) Ammoniacal Silver Nitrate.

 

Part – II

Section – A

(Answer ANY TWO questions)

Q.2.

(a)(i) Find the mole fraction of cane sugar if the molarity of its aqueous solution is 0.4445.

(ii) 3.5 gm of albumin (the most abundant protein in blood) in 100 ml of water produce an osmotic pressure of 0.014 atm at 25º C. Find the molecular weight of albumin. R = 0.0821 dm3 atm K –1 mole –1.                                                                                           [5]

(b) Draw electron dot or any suitable diagram for nitric acid.                                   [1]

Sodium and rock salt have the same structure. State the co-ordination number of Na+ and Cl ion. Explain the effect of the pressure and temperature on the co-ordination number.

[4]

Q.3.

(a) Explain the following :

(i) Zinc displaces hydrogen from acid solution. [E0Zn+2/Zn = – 0.76 volts]

(ii) The hydride of oxygen is a liquid but hydride of sulphur is a gas.                       [3]

(b) Explain the effect of temperature and catalyst on the rate of reaction.                [2]

(c) Illustrate with one example each that water acts as a Bronsted acid and as Bronsted base.                                                                                                                                [3]

(d) Calculate the pH of 0.05 M H2SO4 solution.                                                        [2]

Q.4.

(a) The resistance of a 0.05 M NaOH solution is 31.6 Ω measured in a conductivity cell. At 35º C the constant of the conductivity cell is 0.378 cm –1. Find the molar conductivity of NaOH solution at this temperature.                                                                      [3]

(b) Give reasons for the following :                                                                            [4]

(i) The number of hydrogen chloride in the aqueous solution of acetic acid increases considerably with dilution while this is not the case with the aqueous solution of hydrogen chloride.

(ii) To precipitate metallic hudroxide of group III a mixture of ammonium chloride and ammonium hydroxide is used.

(c) (i) For diamond, state the element present at the lattice site, the number of nearest neighbours for each atom and the type of cell. State the hybridization of the carbon atom in diamond.

(ii) The rate constant of a first order reaction is 4.510–2 sec–1. Calculate the time required for the initial concentration of 0.4 M of the reaction to be reduced to 0.2 M. [3]

 

Section – B

(Answer ANY TWO questions)

Q.5.

(a) Write balanced equations for the following reactions :                                         [3]

(i) Bromine is treated with alkaline hydrogen peroxide.

(ii) Silver is treated with hot and concentrated sulphuric acid.

(iii) Potassium permanganate is heated.

(b) Give reason for the following :                                                                             [2]

(i) Cr+2 is a strong reducing agent whereas Mn+2 is not (Cr = 24, Mn = 25)

(ii) The transition metal ions such as Cu+, Ag+ are colourless.

Q.6.

(a) State the steps in the preparation of potassium dichromate from chromite ore. How does acidified solution of potassium dichromate react with (i) FeSO4 (ii) H2S. Write the balanced equation for the reaction.                                                                                    [4]

(b) Variable oxidation  states are shown by representative elements and transition elements. How is this behaviours different for the two types? Illustrate with one example in each case.                                                                                                                      [1]

Q.7.

(a) Name the following co-ordination compounds using IUPAC names :

(i) [PtCl(NH2CH3)(NH3)2]Cl

(ii) [Cr(NH3)6]+3

(iii) [Ni(NH3)5Cl]NO3

(iv) [Co(CN)3]+3

(v) [Fe(CN)6]–4

(vi) [Co(NH3)4Cl2]+

(b) Write balanced equations for the following reactions:                                          [2]

(i) Bromine water and sodium sulphite.

(ii) Silver sulphide and sodium cynide.

 

Section – C

(Answer ANY TWO questions)

Q.8.

(a) How will you perform the following conversions? Write the relevant equations.

(i) Chloro acetic acid to glycine.                                                                     [3]

(ii) Formic acid to oxalic acid.                                                                        [2]

(iii) Diethyl ether to ethanol.                                                                           [2]

(b) Draw the resonating structures of chlorobenzene.                                                [3]

Q.9.

(a) Identify the reagents for the following conversions :

A                         B                     C                                             D

Benzene → Nitrobenzene → Aniline → Aniline hydrochloride → Benzene diazonium chloride.                                                                                       [3]

(b) Give one example for each of the following name reactions :                              [4]

(i) Hofmann’s Degradation.

(ii) Benzoin condensation.

(iii) Friedel Craft’s Reaction.

(iv) Cannizaro’s Reaction.

(c) Draw the structures of the three isomers which have the same molecular formula C3H8O. Write their names also.                                                                                     [3]

Q.10.

(a) Give one chemical test to distinguish between :                                                   [4]

(i) Glucose and Sucrose.

(ii) Ethanol and Phenol.

(b) Write balanced equation for the following reactions:                                           [4]

(i) Acetone with phosphorus pentachloride.

(ii) Acetic anhydride with ammonia.

(c) Give one example each of addition and condensation. Name the monomer.       [2]

 

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