Pakistan's MCQ Practice Library for Competitive Exams

A. Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat

B. Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature

D. Adiabatic flame temperatures of actual combustions are always less than the maximum values

A. versal jaw crushers

B. Operating principles of Dodge and Blake jaw crushers are combined in the working of

D. er one

E. uction equipments employ

F. There are only four methods namely compression, impact, attrition and cutting, which the size

B. Hammer crushers operate by impact action

C. Standard screens have circular opening

D. With increase in mesh number of screens, their diameter in microns decreases

A. Paramagnetic susceptibility of gases permits the measurement of their concentration

C. O2, NO and NO2 exhibit paramagnetic properties as a result of unpaired electrons

D. Paramagnetic susceptibility of gases decreases with temperature

A. Most of the hydrocarbons are non-polar

C. ionise

D. Generally, non-polar compounds are chemically inactive, conduct electricity poorly and do

E. Molecules with symmetrical arrangements (e.g. CH4 or CCl4) are non-polar

B. In nylon-6, the number 6 represents the total number of carbon atoms in the ring

C. Ethanolamines are produced by using ammonia and ethylene oxide as raw material

D. Catalytic hydrogenation of carbon monoxide produces methyl alcohol

A. In case of a packed tower, the operating velocity is about half of the flooding velocity,

B. idity</strong>

C. Change in barometric pressure does not affect the relative humidity

D. Elution means the desorption of the adsorbed solute by a solvent

F. erally

A. Refractories used for lining electrical furnaces should ordinarily have very low electrical

B. Electrical conductivity of porous refractory material is low

C. ctrical insulators

D. naces</strong>

E. ductivity

A. rogen is 4

C. For a two phase system in equilibrium made up of four non-reacting chemical species, the

D. orisation and sublimation</strong>

E. ber of degrees of freedom is 4

F. Minimum number of degree of freedom of a system is zero

A. Addition of methane to the furnace atmosphere reduces decarburising by hydrogen

C. Active nitrogen (formed by cracking ammonia at the metal surface) cause nitride formation

D. h increase in surface hardness

E. burise the surface of steel at annealing temperatures

F. Nitrogen in presence of steam decor-burises high carbon steel, whereas hydrocarbon gases

A. ther

B. Elutriation process refers to when the soluble material is largely concentrated on the surface of

D. insoluble solid and is simply washed off by the solvent

E. Cellulose acetate membranes are used in dialysis process

F. Cascade means a group of stages interconnected so that various streams flow from one to

A. Tin exists in two allotropic forms

B. The predominant use of tin is in the form of coating for steel & copper alloys

C. Tin can be severely cold worked without the necessity of annealing due to its low recrystallisation temperature

A. Increase in depth of the liquid about the slots increases the plate efficiency, particularly if the liquid depth is < 1"

B. Plate efficiency increases with increase in superficial vapour velocity till entrainment limit

D. Too small a plate spacing can cause a low efficiency, if the vapour velocity is greater than the allowable value

A. For all the cylindrical process vessels operating above atmospheric pressure, formed heads are used for closing the vessel

B. Fouling factor of river water is less than that of sea water

C. Risers provided in bubble cap trays in the distillation column facilitate the flow of both liquid and vapor

A. Adiabatic flame temperatures of actual combustions are always less than the maximum values

B. Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat

D. Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature

A. C.V. of natural gas is about 10000 KCal/Nm3

C. C.V. of LPG is about 26000 kcal/Nm3 (11500 kcal/kg)

D. Main constituents of LPG are propane and butane

A. Cold SBR is superior as compared to hot SBR

C. Polymerisation temperature can modify the properties of SBR

D. Production of cold SBR employs lower pressure as compared to that of hot SBR

A. Addition polymers are generally formed by chain growth polymerisation

C. Bakelite is formed by step growth polymerisation

D. Condensation polymers are generally formed by step growth polymerisation

A. Hydrochloric acid-water

C. Benzene-toluene

D. All A., B. and C.

A. Aluminium sulphate

C. Hydrated lime

D. Ferrous sulphate