WBUT Exam Papers Chemistry-I B Tech Ist Sem 2011-12

WBUT Exam Papers

 Chemistry-I B Tech Ist Sem 2011-12

 

Time Allotted : 3 Hours

Full Marks : 70

The figures in the margin indicate fidi marks.

Candidates are required to give their answers in their own words

as jar as practica ble.

1. Choose the correct alternatives lor any ten of the following :

10×1 = 10

i)               For a reaction A B, both change in enthalpy ( AH ) and change in entropy ( AS ) are positive. The most favourable condition for the reaction is .

a)   low pressure       b) high pressure

c} low temperature d) high temperature.

ii)             Schottky defect is found in

F

I NaCl                                       b) ZnO

AgG1                                  d) FeO, ,

ili) Tetrafluoroethylene is the monomer of

a) Polyethylene                     b) Nylon 6

c) Polyvinyl chloride d) Teflon.

iv)        Normal hydrogen         electrode has been assigned a potential of

a) hundred volts       b) zero volt

c) one volt      d) nene of these.

v)          With the increase in temperature, conductivity of p-type semiconductor

a)          increases

b)          decreases

c)   is changed but the direction of change cannot be

predicted

d)          does not change.

vi)        Which of the following is true for a galvanic cell ?

a)          The cell potential is always negative

b)          The products are less stable than the reactants

c)           AG for the cell reaction is positive

d)           Chemical energy is converted to electrical energy

I065-(N)’

vii)       The most stable carbanion is

a) Ph3c‘                          b) (c6Hu)3c-

c) ( C 3 H 5 ) 3C ‘          d) ( CH 3 ) 3C –

Viii) if iniinite time is required for completion of a chemical reaction, then order of the reaction is

a)                                                                                   zero   b) first

c) second                              d) third.                .

ix)         During mixing, entropy of the surrounding

a)           remains unchanged b) increases

c) decreases                          d) cannot be predicted.

x)          The cell in which the reaction

Fe + CuSO 4 —> FeSO 4 + Cu takes place is

a)           Fe |CuSO4 | | FeSD4 | Cu

b)          Cu | FeSO 4 | | CuSO 4 | Fe

c)           Cu | CuSO 4 | | FeSO 4 | Fe

d)          Fe | FeSO 4 | ] CuSO 4 | Cu

’ ^     3                                  [ Turn over

m) The minimum amount of energy possessed by the

reacting molecules to produce effective collisions is called

a)           threshold energy b)

c) activation energy d)

xii) Proteins are biopolymers. The in them are

a)     aikene   b) amino acid

c)     fatty acid       <j) carbohydrate.

xili) For the redox couples Zn 2+ | Zn ( s } and Cu 2+ | Cu ( s ) the standard reduction potentials are – 076 V and + 0 34 V respectively. If the couples are combined then

a)           Zn 2+ is reduced and Cu is oxidized

b)   Zn is oxidised and Cu 2+ is reduced                •

c)           both Zn and Cu are oxidized

d)          both Zn 2+ and Cu 2+ are reduced.

65-(N)                        a2

GROUP -B ( Short Answer Type Questions )

Answer any three of the following. 3×5 = 15

  1. Deline an adiabatic process and show that for a reversible adiabatic process

( T) c \/R . V – constant.         .

  1. a) Write a short note on bio-diesel.
  2. b)          Define number average molecular weight of a polymer.
  3. c)           What is glass transition temperature of a polymer ?
  1. a) What is the difference between n-type and p-type

semiconductors ?

b)           What do you mean by pseudounimolecular reaction ? Give an example.

  1. a) What is equivalent conductance and what is its unit ?
  2. b)   What is the law of independent imigration of ions ?
  1. a) What is the calorific value of a fuel ?
  2. b)   Distinguish between GCV and NCV.

1065“(N)

GROUP -C ( Long Answer Type Questions )

Answer any three of the following. 3 x 15 = 45

  1. Write notes on any three of the following :

a)           Biodegradable polymer

b)          Clausius-Clayperon equation

c)           Vulcanization of rubber

d)          Calomel electrode

e)           Mesomeric effect

f)             Homogenous catalyst.

  1. a) What is a Carnot cycle ? Obtain the expression for the

efficiency of a reversible Carnot engine and starting from this expression state an appropriate statement of the second law of themodynamics,

b)      What is colour centre generator ? Explain with example.                                  

Discuss the physicochemical principle involved in the measurement of pH of an aqueous solution by Hydrogen electrode method.

Write about the synthesis and uses of the following :

i)            HDPE

ii)          Buna-S- Rubber.

c)           Distinguish between Frenkel and Schottky defect.

ty,

6 + 6 + 3

1065-(N)

10. aj Compose the C-Cl bond length in CH % — CH.Cl and

CH3~CH2-CL

b| Arrange the following in increasing acidity |

If Phenol i

ii]            2, 6~dimethyl-4-mtrophenol

ill) 3, 5 dimethyl-4-nitrophenoI.

c)            Give an example of hyperconjugation with explanation.

d)            Distinguish between the following with example : i) Carbonium ion and carbanion

$ Addition reaction and substitution reaction,

11* a) What are water gas and semi-water gas ?

b)            How do gasoline and diesel differ in chemical composition ?

c)             Deduce the expression for the rate constant of a second order reaction where the initial concentrations of the two reactants are same.                                                                                      .

d)            Discuss the role of solvents in S ^ * reaction.

e)            What is inversion temperature ?

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