VTU Question Papers Engineering Chemistry Degree Examination

 VTU Question Papers Engineering Chemistry

1st & 2nd Sem BE Degree Examination

 

Note: /. Answer any FIVE full questions, selecting at least TWO questions from each part.

  1. Answer all objective type questions only on OMR sheet page No. 5 of the answer booklet.
  2. Answers to the objective type questions on sheets other than OMR will not be valued.

PART-A

i)              If the percentage of hydrogen in a fuel is high, its net calorific value is

A)           High                                                                    B) Low

(c)           Constant                                                          D) Cannot be predicted.

ii)              Which of the following possesses zero octane number

A)            Isooctane

C)                           heptane

iii)         A goodifuel should haveA)           High moisture content

PC)            Moderate ignition temperature

iv)          Photovoltaic cell is a

A)           Storage cell

C)            Energy conversion device

B)   a – methyl naphthalen

D)   Cyclohexane

B)   Low caloric value

D)   High ash content

B)   Rechargeable cell

D)   Fuel cell.

 

What is knocki’ng in 1C engines? Explain its mechanism with chemical reactions. How can it be prevented? I                                                                                                                         (07 Marks)

Explain crystar pulling technique. “ ~                             (                                               (03 Marks)

Calculate gross and net calorific value of a coal sample from the following data:

Weight of coal sample = 0.98 g

Weight of water taken in calorimeter = 2600 g

Water equivalent of calorimeter = 368 g

Latent heat of steam = 2454 J/g

Specific heat of water = 4.187 J/g/K

Rise in temperature = 2.8 K                                                                                 .

Percentage of hydrogen in coal sample = 5.8.                                                                (06 Marks)

2                                               a. i) The standard reduction potential of Zn and Fe are – 0.76 V and – 0.44 V respectively. The emf of cell formed by combining the above two electrodes will be A) -0.32 V B) +0.32 V C)+1.2V                                                                                       D)-1.2V.

ii)            Electrode potential of a metal electrode in a dilute solution is

A)            Same as that in a concentrated solution —

B)             Lower than that in concentrated solution

C)            Higher than that in a concentrated solution

D)            Intermediate.                                       v .

iii)          When the concentration of chloride ion in silver-silver chloride electrode increases, the reduction potential <?f the electrode

A) Increases B) Decreases C) Does not alter D) None of these.

iv)          For a galvanic cell with spontaneous reaction Eccn is assigned

A)           Positive B) Negative C) Zero                                                       D) None of these.

(04 Marl-

r .1


  1. Derive an expression for single electrode potential.                                                             (06 Marks)
    1. What are reference electrodes? How do you construct calomel electrode? Write its half cell reaction and advantages.                                                                                                 . (07 Marks)
    2. The emf of the cell cd | cdS04(0.0093M)||cd(xM)S041 cd is 0.086 V at 25°C. Find the value of X.                                                                                                                                                                                                          (03 Marks)

3           a. i) In which of the following, the net cell reaction is irreversible?

A) Zii – Mn02                                                         B) Pb – H2SO4

C) Ni-MH                                                                D) Ni – Cd.

ii)            To derive maximum voltage from a battery

A)           The difference in the electrode potential must be high.

B)            Internal resistance must be low

C)            The over potential at the electrodes must be low

D)           All the above

iii)         The electrolyte used in solid oxide fuel cell is

A)

r02 + Y2O3   B) Mn02 + ZnO

C)

A1203 + Si02  D) ZnO + Si02.

iv)          WhfCh of the following is used in cellular phone?

A)

Zn – Mn02     B) Pb – acid

C)

Zn-Air                                                           ■ D) Ni-MH.    (04 Marks)

  1. Explain the following battery characteristics i) Capacity ; ii) Cycle life.                          (04 Marks)
  2. Explain the construction and working of Pb – acid battery.                                                 (67 Marks)
    1. Explain the construction and working of H2 – 02 fuel cell. Why is water formed in the above cell removed continuously?                                                                                                             (05 Marks):

 

 

i)              The flux us$d in Galvanising is

A)           NH4CI   B) BaCl2

C)          NaCl      D) Palm oil

ii)            At high hydrogen overvoltage, the rate of corrosion

A)                                                                                                                                                            Increases          B) Decreases

C)

Increases initially and then decreases D) Remains the same.

iii)          Caustic embrittlement in boilers is an example of

A)   Differential metal corrosion B) Pitting corrosion

C)                                                                                                                                                              Water line corrosion D) Stress corrosion

iv)          Which of the following factor accounts for lower corrosion rate?

A)            Large anodic area and small cathodic area

B)            Small anodic and large cathodic area

C)            High temperature •

D)           High humidity.

Explain what type of corrosion occurs when

i)               Steel pipe is connected to copper plumbing

ii)              Presence of small dust particles on iron surface for a long time. Explain the effect of following factors on rate of corrosion

i)              Nature of corrosion product

ii)            Hydrogen over voltage.

What is meant by anodizing? Explain anodizing of aluminium. ^

2 of 4

 

PART-n

i)                In electroplating, complexing agent is used to

A)            Prevent passivation of anode

B)            Prevent the reaction between cathode and plating ion

C)            Get fine grained and adherent deposit

D)            All the above

ii)             Which.of the following is essential in electroless plating?- A) Oxidizing agent                                                       B) Reducing agent

C) Anode                                               D) Electrical energy

iii)          The electrode with lowest hydrogen over voltage is A) Zn       B) Ni

C) Hg                                                      D) Pt

iv)           In electroplating, the article to be plated is subjected to pickling. This is to

A)            Remove grease

B)            Increase the rate of plating

C)            Remove oxide scale

D)            Get a bright deposit.                                                                                            (04 Marks) Explain the effect of following factors on nature of electrodeposit

i)                Current density

ii)             Throwing power.                                                                ,                                           (06 Marks) Explain electroplating of gold. Mention its applications. (04 Marks) What is electroless plating? Explain electroless plating of Cu. (06 Marks)

i)               Which of the following is the criterion for a molecule to exhibit liquid crystalline behaviour?

A)           Flexible from one end to the other                                 t

B)           Rigid from one end to the other                                                                    (

C)           Flexible terminals and rigid central core

D)           Flexible central core and rigid terminal.

ii)            Which of the following sequential changes occur when liquid crystals of MBBA series are heated?

A)           Isotropic phase —> Smectic phase -> Anisotropic phase

B)           Anisotropic phase -» Nematic phase ->• Isotropic phase

C)           Anisotropic phase -» Isotropic phase -» Cholestric phase

D)           Smectic phase -» Anisotropic phase -» Isotropic phase.

iii)          Absorbance of light by a solution of substance depends on

A)            Path length

B)            Concentration of solution

C)            Wave length of incident light

D)            All the above

iv)          Conductometric estimation is based on

A)           Beer – lambert’s law

B)            Henderson – Hesselbalch equation

C)              Nem’st equation

D)           Ohm’s law.                                                                                                           (04 Marks) What are liquid crystals? Explain the classification of liquid crystals. (06 Marks) Explain the principle and application of potentiometry with respect to Redox titration.

(07 Marks)

Mention advantages of conductometric titration.                                                             (03 Marks)

 

  1. i) Which of the following is a copolymer?

A) Polythene                        .                                 B) Polyurethane

C)                                                                                                                                                           Teflon        D) Plexi glass

ii)              Which of the following is the requirement for conductivity in polymer

A) Linear structure                                                B) Presence of oxidizing or reducing agents

C)                                                                                                                                                         Conjugation                                                          D) All these                                                                                 t

iii)           Chemical resistance of a polymer decreases with

A) Increase in crystallinity                                  B) Increase in cross-linking

■C) Increase in molecular mass                          D) None of these

iv)            Micells are formed in

A)           Bulk polymerization            B) Solution                                                                                                                                                                                                                                                                                         ,

C)      Emulsion polymerization                    D) Suspension polymerization.                                                                                                                                    D) Suspension polymerization. (04 Marka?),

  1. Explain the free radical mechanism of addition polymerization taking ethane as an example.

(06 Marks) !

  1. Explain the mechanism of conduction in polyacetylene.                                                          (04 Marks)!
  2. Explain the manufacture of following polymers and mention their uses

i)                Polymethylmethacrylate

ii)             Neoprene.                                                                                                                               (06 Marksjj

 

 

The reagent used in the estimation of sulphate ions in water is

A)             Phenoldisulphonic acid

B)             Zr- SPADNS

C)             Ammonia

D)             Barium chloride Alkalinity in water is not due to A) H

C)             CO]~

Potable water is totally devoid of A) Pathogenic bacteria

C)             Chlorides

 

in the determination of dissolved oxygen in water by Winkler’s method, sodium is added to

A) Liberate I2                                                        B) Oxidize KI

Destroy nitrites D) React with starch.

 

 Explain coiourirnetric estimation of nitrate ion in water.

Calculate COD of effluent sample when 25 cm3 of effluent requires 0.001 M K.2Cr207 for complete oxidation.

Define BOD. Explain activated sludge treatment.

 


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