HindustanAeronauticsLtd. Chemical-Engineering Contributed by Keshav updated on Jun 2019
Placement Paper |   9077


HAL  - Chemical Engineering objective type question for practice HAL Model questions for all engineering solved question papers,HAL Chemical engineering Mechanical Operations multiple choice objective type questions


1. Shape factor for a cylinder whose length equals its diameter is

(a) 1.5     (Ans)

(b) 0.5

(c) 1.0

(d) 2.0


2. The ratio of the actual mesh dimension of Taylor series to that of the next smaller screen is

(a) 2

(b) √2     (Ans)

(c) 1.5

(d) √3


3. The opening of a 200 mesh screen (Taylor series) is

(a) 0.0074 cm     (Ans)

(b) 0.0074 mm

(c) 0.0047 cm

(d) 74 mili-microns


4. The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is

(a) 1.5

(b) 1

(c) √2

(d) none of these      (Ans)


5. Cumulative analysis for determining surface is more precise than differential analysis, because of the

(a) assumption that all particles in a single fraction are equal in size.

(b) fact that screening is more effective.

(c) assumption that all particles in a single fraction are equal in size, is not needed.       (Ans)

(d) none of these.


6. Equivalent diameter of a particle is the diameter of the sphere having the same

(a) ratio of surface to volume as the actual volume.      (Ans)

(b) ratio of volume to surface as the particle.

(c) volume as the particle.

(d) none of these


7. For coarse reduction of hard solids, use

(a) impact

(b) attrition

(c) compression     (Ans)

(d) cutting


8. Soft & non-abrasive materials can be made into fines by

(a) attrition      (Ans)

(b) compression

(c) cutting

(d) none of these


9. Crushing efficiency is the ratio of the

(a) surface energy created by crushing to the energy absorbed by the solid.      (Ans)

(b) energy absorbed by the solid to that fed  to the machine.

(c) energy created by crushing.

(d) energy absorbed by the solid to the surface energy created by crushing.


10. Rittinger's crushing law states that

(a) work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product.

(b) work required to form a particle of a particular size is proportional to the square root of the surface to volume ratio of the product.

(c) work required in crushing is proportional to the new surface created.      (Ans)

(d) for a given machine and feed, crushing efficiency is dependent on the size of the feed & product.


11. Bond crushing law

(a) calls for relatively less energy for the smaller product particles, than does the Rittinger law.      (Ans)

(b) is less realistic in estimating the power requirements of commercial crushers.

(c) state that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product.

(d) states that the work required for the crushing is proportional to the new surface created.


12. Work index is defined as the

(a) gross energy (k Wh/ton of feed) needed to reduce very large feed to such a size that 80% of the product passes through a 100 micron screen.      (Ans)

(b) energy needed to crush one tonne of feed to 200 microns.

(c) energy (k Wh/ton of feed) needed to crush small feed to such a size that 80% of the product passes a 200 mesh screen.

(d) energy needed to crush one ton of feed to 100 microns.


13. The operating speed of a ball mill should be  ......... the critical speed.

(a) less than      (Ans)

(b) much more than

(c) at least equal to

(d) slightly more than


14. A fluid energy mill is used for

(a) cutting

(b) grinding

(c) ultragrinding      (Ans)

(d) crushing


15. Wet grinding in a revolving mill .... as compared to dry grinding.

(a) gives less wear on chamber walls

(b) requires more energy

(c) increases capacity      (Ans)

(d) complicates handling of the product


16. Cement clinker is reduced to fine size by a

(a) roll crusher

(b) ball mill

(c) tube mill      (Ans)

(d) hammer mill


17. Mixer used for rubber compounding is

(a) mixer-extruder

(b) banbury internal mixer      (Ans)

(c) muller mixer

(d) pug mill


18. Molten ammonium nitrate is mixed with ground limestone in fertilizer plant in a

(a) pug mill      (Ans)

(b) mixer-extruder

(c) banbury mixer

(d) muller mixer


19. For the preliminary breaking of hard rock, we use a

(a) gyratory crusher      (Ans)

(b) ball mill

(c) tube mill

(d) squirrel-cage disintegrator


20. Fibrous material is broken by a

(a) roll crusher

(b) squirrel-cage disintegrator      (Ans)

(c) ball mill

(d) tube mill


21. Ribbon blenders are exclusively meant for

(a) blending miscible liquids.

(b) non-flowing powder and thin pastes.      (Ans)

(c) bath mixing.

(d) continuous mixing.


22. As the product becomes finer, the energy required for grinding

(a) decreases

(b) increases     (Ans)

(c) is same as for coarser grinding

(d) is 1.5 times that for coarser grinding


23. Increasing the capacity of a screen ....... the screen effectiveness.  

(a) decreases      (Ans)

(b) increases

(c) does not effect

(d) none of these


24. Screen efficiency is

(a) recovery/rejection

(b) recovery

(c) rejection

(d) none of these      (Ans)


25. Traces of solids are removed from liquid in a

(a) classifier

(b) clarifier      (Ans)

(c) sparkler filter

(d) rotary vacuum filter


26. For classification of potable (drinking) water, we use a ...... filter.

(a) gravity sand      (Ans)

(b) plate and frame

(c) vacuum leaf

(d) rotary vacuum


27. Vacuum filter is most suitable for the

(a) removal of fines form liquid.

(b) liquids having high vapour pressure.

(c) liquids of very high viscosity.

(d) none of these      (Ans)


28. Filter aid is used to

(a) increase the rate of filtration.

(b) decrease the pressure drop.

(c) increase the porosity of the cake.      (Ans)

(d) act as a support base for the septum.


29. Filter medium resistance is that offered by the

(a) filter cloth.

(b) embedded particles in the septum.

(c) filter cloth and the embedded particle collectively.      (Ans)

(d) none of theses.


30. Filter medium resistance is important during the ......... of filtration.

(a) early stages.      (Ans)

(b) final stages.

(c) entire process.

(d) none of these


31. Cake resistance is

(a) important in the beginning of filtration.

(b) decreased with the time of filtration.

(c) independent of pressure drop.

(d) none of these.     (Ans)


32. During the washing of cake

(a) all the resistance are constant.      (Ans)

(b) filter medium resistance increases.

(c) filter medium resistance decreases.

(d) cake resistance decreases. 


33. The porosity of a compressible cake is

(a) minimum at the filter medium.      (Ans)

(b) minimum at the upstream face.

(c) maximum at the filter medium.

(d) same throughout the thickness of cake.


34. The unit of specific cake resistance is

(a) gm/cm2     (Ans)

(b) cm/gm

(c) cm/gm2

(d) gm/cm


35. The filter medium resistance is controlled by

(a) pressure drop alone

(b) flow rate alone

(c) both pressure drop and flow rate      (Ans)

(d) cake thickness


36. Compressibility co-efficient for an absolutely compressible cake is

(a) 0

(b) 1     (Ans)

(c) 0 to 1

(d) ∞


37. In continuous filtration (at a constant pressure drop), filtrate

(a) square root of the velocity.      (Ans)

(b) square of the viscosity.

(c) filtration time only.

(d) washing time only.


38. For separation of sugar solution from settled out mud, we use a ......... filter.

(a) sparkler

(b) plate and frame

(c) centrifugal      (Ans)

(d) rotary drum vacuum


39. Moisture can be removed from lubricating oil using

(a) tubular centrifuge      (Ans)

(b) clarifier

(c) sparkler filter

(d) vacuum leaf filter


40. Dust laden air can be purified using a

(a) cyclone separator      (Ans)

(b) bag filter

(c) gravity settler

(d) tubular centrifuge



41. The most common filter aid is

(a) diatomaceous earth      (Ans)

(b) calcium silicate

(c) sodium carbonate

(d) silica gel


42. To remove very small amount of tiny solid impurities from liquid, we use a

(a) pressure filter

(b) vacuum filter

(c) centrifugal filter

(d) coagulant      (Ans)


43. Removal of activated carbon from glycerin is done by

(a) plate and frame filter      (Ans)

(b) rotary vacuum filter

(c) batch basket centrifuge

(d) none of these


44. Filtration of water in a paper mill is done by a/an ....... filter.

(a) open sand      (Ans)

(b) plate and frame

(c) vacuum leaf

(d) sparkler


45. The speed of a rotary drum vacuum filter may be about ..... rpm.

(a) 1     (Ans)

(b) 50

(c) 100

(d) 500


46. Gelatinous solid (which plug the septum) can be filtered by a ... filter.

(a) sparkler

(b) plate and frame

(c) vacuum leaf

(d) precoat      (Ans)


47. To remove dirt from the flowing fluid, we use a

(a) coagulant

(b) gravity settler

(c) strains      (Ans)

(d) clarifier


48. As particle size is reduced

(a) screening becomes progressively more difficult.      (Ans)

(b) screening becomes progressively easier. 

(c) capacity and effectiveness of the screen is increased.

(d) none of these.


49. For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid?

(a) Kozney-Karman equation      (Ans)

(b) Leva's equation

(c) Blake-Plummer equation

(d) none of these


50. A screen is said to be blinded, when the

(a) oversizes are present in undersize fraction.

(b) undersizes are retained in oversize fraction.

(c) screen is plugged with solid particles.      (Ans)

(d) screen capacity is abruptly increased

Chemical Process Industries  (Chemical Technology)

 1. Catalyst used in the manufacture of sulphuric acid by chamber & contact processes are respectively

(a) V2O5 & Cr2O3.

(b) oxides of nitrogen & Cr2O3.

(c) V2O5 on a porous carrier & oxides of nitrogen.

(d) oxides of nitrogen & V2O5 on a porous carrier.     (Ans)


2. In contact process, SO3 is absorbed in 97% H2SO4 and not in water, because

(a) SO3 gas is sparingly soluble in water.

(b) water forms an acid mist, which is difficult to absorb.     (Ans)

(c) the purity of acid is affected.

(d) scale formation in the absorbed is to be avoided.


3. Contact process of sulphuric acid manufacture

(a) yields acid of higher concentration than chamber process.     (Ans)

(b) yields acids of lower concentration than chamber process.

(c) is obsolete.

(d) eliminates absorber.


4. 20% oleum means that in 100 kg oleum, there are 20 kg of

(a) SO3 and 80 kg of H2SO4.     (Ans)

(b) H2SO4 and 80 kg of SO3.

(c) SO3 for each 100 kg of H2SO4.

(d) none of these


5. Producer gas consists mainly of

(a) CO, CO2N2, H2    (Ans)

(b) CO, H2

(c) H2, CH4

(d) C2H2, CO2, H2


6. Oxygen is produced by fractionation of air using ......... process.

(a) Linde's

(b) Claude's

(c) either (a) or (b)     (Ans)

(d) none of these


7. Raw materials for 'Solvay Process' for manufacture of the soda ash are

(a) salt, limestone and coke or gas.     (Ans)

(b) ammonia, salt and limestone.

(c) ammonia limestone and coke.

(d) none of these.


8. Economics of 'Solvay Process' depends upon the efficiency of

(a) carbonating tower

(b) ammonia recovery

(c) ammonia recovery and size of the plant     (Ans)

(d) ammoniation of salt solution


9. Mercury cells for caustic soda manufacture, compared to diaphragm cells

(a) require lower initial investment.

(b) require more power.

(c) produce lower concentration NaOH.

(d) none of these     (Ans)


10. Cement mainly contains

(a) CaO, SiO2, Al2O3    (Ans)

(b) MgO, SiO2, K2O

(c) Al2O3, MgO, Fe2O3

(d) CaO, MgO, K2O


11. Gypsum is chemically

(a) calcium chloride

(b) potassium sulphate

(c) sodium sulphate

(d) calcium sulphate     (Ans)


12. Glauber's salt is chemically

(a) calcium sulphate

(b) potassium sulphate     (Ans)

(c) potassium chlorate

(d) none of these


13. Permanent hardness of water is due to the presence of calcium & magnesium

(a) bi-carbonates

(b) sulphates & chlorides     (Ans)

(c) carbonate

(d) none of these


14. Widely used method for the conditioning of boiler feed water is the

(a) cold lime process

(b) coagulation

(c) hot-lime soda process     (Ans)

(d) sequestration


15. Hydrazine is largely used

(a) as a starting material for 'hypo'.

(b) in photographic industry.

(c) as rocket fuel.     (Ans)

(d) in printing industry.


16. Trinitro-toluene (TNT) is

(a) used in glycerine manufacture.

(b) an explosive.     (Ans)

(c) used in dye manufacture.

(d) none of these.


17. Oil is a/an

(a) mixture of glycerides.

(b) mixture of glycerides of fatty acids.     (Ans)

(c) solid at normal temperature.

(d) ester of alcohols other than glycerine.


18. Wax is a

(a) mixture of glycerides.

(b) mixture of esters of polyhydric alcohols excepting glycerine.     (Ans)

(c) liquid at room temperature.

(d) mixture of glycerides of fatty acids.


19. Unsaturated oils compared to saturated oils have

(a) lower melting point & higher reactivity to oxygen.    (Ans)

(b) higher melting point & higher reactivity to oxygen.

(c) higher melting point & lower reactivity to oxygen.

(d) higher melting point & lower reactivity to oxygen.


20. Rancidity of the fatty oil can be reduced by its

(a) decoloration

(b) hydrogenation     (Ans)

(c) oxidation

(d) purification


21. Solvent used for extraction of oil is

(a) hexane     (Ans)

(b) methyl ethyl ketone

(c) furfurol

(d) none of these


22. Solvent extracted oil

(a) has low free fatty acid content.

(b) is odourless.

(c) has more of unsaturates.

(d) none of these     (Ans)


23. Hydrogenation of oil does not

(a) remove double bonds.

(b) raise its melting point.

(c) improve its resistance to oxidation.

(d) none of these     (Ans)


24. Catalyst used in the hydrogenation of oil is

(a) nickel     (Ans)

(b) platinum

(c) iron

(d) alumina


25. Soaps remove dirt by

(a) increasing the surface tension.

(b) decreasing wettability.

(c) supplying hydrophyllic group.

(d) none of these     (Ans)


26. Metallic soap is ........ salt of fatty acids.

(a) sodium

(b) potassium

(c) both sodium & potassium

(d) aluminium or calcium     (Ans)


27. Fat splitting catalyst is

(a) CaCO3

(b) ZnO    (Ans)

(c) Al2O3

(d) Fe


28. Free alkali in a toilet soap is ........ that in a laundary shop.

(a) less than     (Ans)

(b) more than

(c) same

(d) none of these


29. Soap cannot be used with hard water, because

(a) hard water contains sulphate.

(b) they form insoluble calcium soaps which precipitate.     (Ans)

(c) they attract back the removed dirt.

(d) none of these.


30. Builders are added in soap to act as

(a) cleaning power booster     (Ans)

(b) anti-redeposition agent

(c) corrosion inhibitor

(d) fabric brightener


31. Bio-degradable detergents 

(a) can be readily oxidised.     (Ans)

(b) pose problem in sewerage plant.

(c) have an isoparaffinic structure.

(d) should not be used as it spoils the cloth.


32. Which of the following is a detergent ?

(a) Fatty alcohol

(b) Alkyl benzene sulphonate (ABS)     (Ans)

(c) Fatty acids

(d) Methylene chloride


33. Yellow glycerine is made into white, using

(a) activated carbon     (Ans)

(b) diatomaceous earth

(c) bauxite

(d) bentonite


34. Essential oils are usually obtained using

(a) steam distillation     (Ans)

(b) extractive distillation

(c) solvent extraction

(d) leaching


35. Plasticisers are added to paints to

(a) make it corrosion resistant.

(b) make glossy surface.

(c) give elasticity & prevent cracking of the film.     (Ans)

(d) increase atmospheric oxidation.


36. Which oil is preferred for paint manufacture ?

(a) Drying oil     (Ans)

(b) Non-drying oil

(c) Semi-drying oil

(d) Saturated oil


37. Function of thinner in a paint is to

(a) accelerate the oxidation of oil.

(b) prevent gelling of the paint. 

(c) suspend pigments & dissolve film forming materials.     (Ans)

(d) from a protective film.


38. Varnish does not contain

(a) pigment     (Ans)

(b) thinner

(c) dryer

(d) anti-skimming agent.


39. Enamels

(a) give good glossy finish.     (Ans)

(b) are same as varnish.

(c) are prepared from non-drying oil.

(d) do not contain pigment.


40. SO2 is bubbled through hot sugar cane juice to

(a) act as an acidifying agent.     (Ans)

(b) increase its concentration.

(c) increase the amount of molasses. 

(d) increase the crystal size.


41. Molasses is the starting material for the production of

(a) alcohol     (Ans)

(b) essential oil

(c) fatty acids

(d) massecuite


42. The enzyme which converts starch into the disacharides maltose is 

(a) diastase     (Ans)

(b) maltase

(c) yeast

(d) none of these


43.  The ideal pulp for the manufacture of paper should have high ........... content.

(a) ellulose     (Ans)

(b) lignin

(c) both (a) & (b)

(d) none of these


44. In Kraft process of paper manufacture, white cooking liquor consists of caustic soda

(a) sodium sulphide & sodium carbonate.     (Ans)

(b) sodium sulphite & sodium carbonate.

(c) sodium sulphite & sodium sulphide.

(d) none of these


45. Comparing sulphate process with sulphite process, we find that ........... in the later.

(a) both temperature & pressure in the former is less than that

(b) both temperature & pressure in the former is more than that     (Ans)

(c) temperature is more in the former whereas pressure is more

(d) pressure is more in the former whereas temperature is less


46. Cooking liquor in case of sulphite process is

(a) sodium sulphite and sodium bisulphite.     (Ans)

(b) magnesium sulphite and free SO2 in acid medium.

(c) magnesium sulphate and magnessium bicarbonate.

(d) none of these


47. Which is a high grade pulp ?

(a) Rag pulp

(b) Mechanical pulp

(c) Sulphate pulp     (Ans)

(d) Sulphite pulp


48. Which of the following paper does not require a filler during manufacture ?

(a) Bond paper

(b) Writing paper

(c) Blotting paper     (Ans)

(d) Coloured paper


49. Bleaching of paper pulp is done with

(a) activated clay

(b) bromine

(c) chlorine or chlorine dioxide     (Ans)

(d) magnesium sulphite


50. Sizing material is incorporated in paper to

(a) impart resistance to penetration by liquids.     (Ans)

(b) increase its thickness.

(c) increase its flexibility & opacity.