Category: Pulp & Paper Objective Questions

Pulp and Paper Multiple Choice Questions on “Fiber Penetration and Approach”.

1. _________ is a measure of the solids content and the dry weight of fibers and other solids divided by the net wet weight of stock weight and expressed as a percentage.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: b
Clarification: Consistency is a measure of the solids content and the dry weight of fibers and other solids divided by the net wet weight of stock weight and expressed as a percentage. The consistency of stock at the headbox can be as low as 0.3%.

2. _________ are large mixing vessels utilized to dis-integrate purchased pulp, broke, and recycled paper into a relatively dilute slurry which can be processed inside the mill.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: c
Clarification: Hydrapulpers are large mixing vessels utilized to dis-integrate purchased pulp either wet lap at 50 percent solids or dry sheets at 80-85 percent solids, broke is the paper that must be re-processed inside the mill, and recycled paper into a relatively dilute slurry which can be processed within the mill.

3. The _________ is a disturbed storage test that holds back stock prior to being sent to the paper making process.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: a
Clarification: The machine chest is a disturbed storage test that holds back stock prior to being sent to the papermaking process. If the any other equipment shuts down temporarily, the paper machine could continue running by drawing pulp from the machine chest.

4. The _________ is a mini box in which pulp enters prior to the fan pump for utilized in the paper machine.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: d
Clarification: The stuff box is a mini box that pulp enters prior to the fan pump for use in the paper ma chine. Pulp enters at a regulated 3-4 percent consistency through a stock or stuff valve and maintains a constant head to precisely control the flow rate to the fan pump.

5. Stock and re-circulated white water are not mixed together at the primary fan pump, a very large pump.
a) True
b) False
Answer: b
Clarification: Stock and re-circulated white water are not mixed together at the primary fan pump, a very large pump.

6. The _________ is a device for the stock going to a paper machine with a partial vacuum.
a) Machine chest
b) Deculator
c) Hydrapulper
d) Stuff box
Answer: b
Clarification: The deculator’s a device for the stock going to a paper machine with a partial vacuum. This causes small air bubbles that are entrained in the stock to expand, separate from the stock, and come to the surface of the stock. Dissolved gases will also be removed to some extent.

7. Pulp is screened through small holes or slots to remove shives, dirt, and other large particles. The reject material is usually refined and screened, and the final rejects discarded to the sewer system.
a) True
b) False
Answer: a
Clarification: Pulp’s screened through small holes or slots to remove shives, dirt, and other large particles. The rejected material is usually refined and screened, and the final rejects discarded to the sewer system. Vibratory flat screens and rotary screens are open, gravity flow systems, which could have high frequency vibration to help the screening action.

8. _________ were introduced in the 1950s for headbox approach systems and were enclosed, pressurized screens of high capacity.
a) Lining screen
b) Content screen
c) Head box
d) Pressure screens
Answer: d
Clarification: Pressure screens were introduced in the 1950s for headbox approach systems and were enclosed, pressurized screens of high capacity which demonstrates the principle of operation as do Plates 30 to 32. One crucial modification was that the reduction in the screen slot width from 0.50 mm (0.020 in.) prior to 1970, which is still utilized for corrugating medium.

9. What is the name of the instrument?

a) Rotator cleaner
b) Centrifugal cleaner
c) Binary cleaner
d) Conical cleaner
Answer: b
Clarification: Centrifugal energy which is produced when parts are rotated inside a sealed process chamber, provides thorough penetration, solubilization, and contaminant removal .

10. What is the name of the hidden content?

________ = {(weight of dry material) / (weight of suspension)} x 100%

a) Stuff box
b) Consistency
c) Fan pump
d) Machine chest
Answer: b
Clarification: Consistency’s a calibration of the solids content which is the dry weight of fibers and other solids divided by the total wet weight of stock weight and expressed as a percentage. It could be as low as 0.3%.

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Pulp and Paper Multiple Choice Questions on “Kraft Liquor Calculations”.

1. The _________ is the sum of all of the Na salts in the liquors (as Na₂O) that contribute to AA in the kraft cycle, specifically NaOH, Na₂S, Na₂CO₃, and Na₂O.
a) Base
b) Total alkali
c) Total acid
d) Buffer
Answer: b
Clarification: The total alkali’s the sum of all of the Na salts in the liquors (as Na₂O) that are capable of being converted to AA in the kraft cycle, specifically NaOH, Na₂S, Na₂CO₃, and Na₂O.

2. _________ is the sum of all of the bases in the white liquor that could be titrated with strong acid.
a) Total titratable alkali
b) Active alkali
c) Total chemical
d) Total alkali
Answer: a
Clarification: T.T.A. is the sum of all of the bases in the white liquor that could be titrated with strong acid. It’s considered as NaOH, Na₂S, and Na₂CO₃ (as Na₂O), although small amounts of Na₂CO₃.

3. The sum of the active ingredients in the pulping process is called active alkali.
a) True
b) False
Answer: a
Clarification: White liquor’s a strongly alkaline sol. mainly of NaOH and Na₂S. It’s utilized in the first stage of the Kraft process in which lignin and hemicellulose are separated from cellulose fiber for the production of pulp.

4. _________ is the sum of Na chemicals that will produce OH^– during kraft pulping.
a) Active akali
b) Effective alkali
c) Causticity
d) Sulfidity
Answer: b
Clarification: NaOH is completely ionized and for every 2 sodium atoms of Na₂S, there’ll be one OH^– produced.

5. In the _________ sulfidity’s the ratio of Na₂S to the active alkali, expressed as a %.
a) Green liquor
b) Red liquor
c) White liquor
d) Black liquor
Answer: c
Clarification: Generally, a mill runs in the vicinity of 25 to 30% sulfidity, depending largely on the wood species pulped. Sulfidity inc. the rate of de-lignification, which occurs by nucleophilic action of the hydrosulfide anion (H.S.) and appears to protect cellulose against degradation.

6. The _________ is the ratio of NaOH to active alkali, expressed as a %.
a) Active alkali
b) Liquor to wood ratio
c) Causticity
d) Sulfidity
Answer: c
Clarification: The causticity’s the ratio of NaOH to active alkali, depicted as a percentage; therefore, causticity + sulfidity = 100%. The term sulfidity’s utilizes much more than the term causticity, and both give the same information.

7. The _________ is the ratio of NaOH to NaOH and Na₂CO₃.
a) Sulfidity
b) Causticity
c) Causticizing efficiency
d) Reduction efficiency
Answer: c
Clarification: This is a calculation of how efficient causticizing is; it represents the percentage of the Na₂CO₃ from the recovery boiler that is converted back into useful NaOH cooking chemical. A value of 77-80% is typical.

8. The ratio of Na₂S to the sum of Na₂S and Na₂SO₄ in green liquor expressed as a percentage. What’s the name of the topic?
a) Sulfidity
b) Causticity
c) Causticizing efficiency
d) Reduction efficiency
Answer: d
Clarification: The reduction efficiency’s the ratio of Na₂S to the sum of Na₂S and Na₂SO₄ in green liquor expressed as a %. This’ a calc. of the reduction efficiency in the recovery boiler. This value should be high, as 95 percent, and is not routinely measured in the mill.

9. Derive the conversion factor of 0.775 utilized to express the weight of NaOH on an Na₂O basis.
a) 0.775 g Na₂O
b) 3.254 g Na₂O
c) 15.775 g Na₂O
d) 0.456 g Na₂O
Answer: a
Clarification: 1st, the molar relationship b/w these 2 species is expressed.
2 NaOH andbarr; Na₂O + H₂O
Gravimetric factor’s determined as follows:
1g NaOH X 1 mol NaOH(40g NaOH)^-1 x 1 mol Na₂O(2 mol NaOH)^-1 x 62g Na₂O(1 mol Na₂O)^-1 = 0.775g Na₂O.

10. Fill in the blank.
________ = {(NaOH) / (NaOH + Na₂CO₃)} x 100%
a) Na₂CO₃
b) NaOH
c) CO₃
d) Na
Answer: b
Clarification: The causticizing efficiency is the ratio of NaOH to NaOH and Na₂CO₃. This’s a calculation of how efficient causticizing is; it represents the percentage of the Na₂CO₃ from the recovery boiler that’s converted back into useful NaOH cooking chemical. A value of 77 to 80% is typical.

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Pulp and Paper Multiple Choice Questions on “Surface Tension and Sizing”.

1. Identify the equation used to calculate pore sizes.

l² = rty cosθ/2ŋ

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: a
Clarification: Lucas used this equation to calculate pore sizes in paper based on the speed of the rise of organic liquids in paper strips. Lucas used organic liquids since they would not change the pore sizes by swelling or hydration.

2. Identify the equation to give actual capillary action.

P^α – P^β= 2y / R

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: b
Clarification: This equation is modified to give the actual capillary rise for H₂O by solving for the force of H₂O and the wettability of the glass by the H₂O. If the H₂O completely wets the glass. Here, r is the capillary tube radius, p is the density of a phase, g is the acc. due to gravity, and h is the height of the H₂O.

3. Identify the equation to give actual capillary action.

y = 1/2(ρ_α – ρ_β)ghr / cosθ

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: b
Clarification: This equation is modified to give the actual capillary rise for H₂O by solving for the force of H₂O and the wettability of the glass by the H₂O. If the H₂O completely wets the glass. Here, r is the capillary tube radius, p is the density of a phase, g is the acc. due to gravity, and h is the height of the H₂O.

4. 3 contact angles of a droplet on a flat surface

a) True
b) False
Answer: a
Clarification: Either at 90 degrees or an acute angle or an obtuse angle. Contact angel is the angle, normally measured through the liquid, where a liquid–vapor interface contacts a solid surface.

5. Find the hidden term

if adhesive > cohesive then 0 degree

a) 10 degrees
b) 180 degrees
c) 100 degrees
d) 90 degrees
Answer: d
Clarification: The contact angle is a measure of the adhesive force of the liquid with the surface relative to the cohesive forces in the liquid. It is generally measured through the liquid, where a liquid–vapour interface contacts a solid surface.

6. Find the hidden term

if adhesive > cohesive then 90 degree

a) 10 degrees
b) 180 degrees
c) 100 degrees
d) 90 degrees
Answer: b
Clarification: The contact angle is a measure of the adhesive force of the liquid with the surface relative to the cohesive forces in the liquid. The angle, conventionally measured through the liquid, where a liquid–vapour interface contacts a solid surface.

7. _________ is easily wetted by H₂O and, H₂O on _________ gives a low contact angle that approaches zero; this causes the water to be drawn into the capillaries. [/expand]
a) Starch
b) Lignin
c) Cellulose
d) Pulp
Answer: c
Clarification: Cellulose is easily wetted by H₂O and, H₂O on cellulose gives a low contact angle that approaches zero; this causes the H₂O to be drawn into the capillaries.

8. Internal sizing agents are generally _________ materials. The polar portion attaches to the fiber or fines directly through a covalent bond or indirectly through a caustic element such as alum.
a) Amphoteric
b) Amphitaric
c) Non polar
d) Polar
Answer: b
Clarification: Internal sizing agents are generally amphipathic having polar and nonpolar moieties on the same molecule materials. The polar portion more importantly, it is chemically reactive attaches to the fiber or fines directly through a covalent bond.

9. Identify the equation used to calculate pore radius from which water will condense.

r = (2yV) / RT ln (p_o/p)

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: a
Clarification: A water droplet with a (+ve) radius has a slightly higher vapor pressure than a flat surface of H₂O. When with a (-ve) radius has a lower vapor pressure, which allows condensation to occur.

10. Inverse _________has been utilized to characterize surface energy; in pulp and paper this has been accomplished with treated and untreated pulps.
a) Gas chromatography
b) Silver test
c) Stone test
d) Sulfurication
Answer: a
Clarification: It’s a common type of chromatography utilized in analytical chemisty for separating and analyzing compounds that could be vaporized without decomposition. Typical uses of G.C. include testing the purity of a particular substance, or separating the different components of a mixture.

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Pulp and Paper Multiple Choice Questions on “Behavior of Light Rays”.

1. If a beam of light travelling in a vacuum strikes a flat surface of a transparent material at an angle of incidence φ_a relative to normal some of the light will be reflected at angle φ_r
a) True
b) False
Answer: a
Clarification: If a beam of light travelling in a vacuum when air is close enough strikes a flat surface of a transparent material at an angle of incidence φ_a relative to normal some of the light will be reflected at angle φ_r, and some of the light will be transmitted to the object at angle φ_b.

2. It is known that the angle of refraction from normal isn’t equal to the angle of the incident light from normal (φ_a = φ_r)
a) True
b) False
Answer: b
Clarification: It is known that the angle of reflection from normal is equal to the angle of the incident light from normal (φ_a = φ_r). It’s also known that the sin φ_a/sin φ_b, = n of the transparent material.

3. If any refracted light were to travel the same path backward the same relationship would exist, that is__________ = n.( The angle of reflection for normal is (φ_a = φ_r))
a) sin φ_a/cos φ_b
b) cos φ_a/sin φ_b
c) cosec φ_a/sin φ_b
d) sin φ_a/sin φ_b
Answer: d
Clarification: The incident, reflected, and refracted rays and the normal line are all in the same plane. Refracted light travels to the same path backward the same relationship would exist, that is sin φ_a/sin φ_b, = n.

4. __________ means that when light travels from a material of less index of refraction to a material of higher index of refraction, the light is bent towards the normal.
a) Reflection
b) Refraction
c) Radiation
d) Plunge
Answer: b
Clarification: The refraction of light when it passes from a fast medium to a less dense medium bends the light ray toward the normal to the boundary b/w the two media. The converse is also true. na sin φ_a=nb sin φ_b.

5. With __________ it’s possible that a light ray will be reflected back into a material when striking at a higher angle.
a) TIR
b) TIM
c) CPR
d) VIBGYOR
Answer: a
Clarification: The complete reflection of a light ray touching an interface with a less dense medium when the angle of incidence exceeds the critical angle. It’s the phenomenon that keeps light inside glass fiber cables so that it could be transmitted large distances with relatively little loss of intensity.

6. It is known that the maximum amount of scattering results when the minimum particle dimension is about 1.5 the wavelength of the light being __________
a) Scattering
b) Shaping
c) Tyndell
d) Intensity
Answer: a
Clarification: Light scattering could be thought of as the deflection of a ray from a straight path, for eg. by irregularities in the propagation medium, particles, or in the interface b/w two media. This corresponds to about 0.25 jLtm, which is a common size for certain fillers.

7. __________ has very high absorbance across the spectrum and so little light is reflected or transmitted.
a) White paper
b) Grey paper
c) Black paper
d) Red paper
Answer: c
Clarification: Gray one has some absorbance which is nearly constant across the visible light spectrum. Gray or white is said to be achromatic (without color) and has a flat spectral reflectance curve.

8. __________ paper scatters light very little and has relatively less absorbance so that most light is transmitted through it, unless it is very thick.
a) Cellophane
b) Latex
c) Glassine
d) Plastic
Answer: c
Clarification: It’s a smooth and glossy paper that is air, H₂O and grease resistant. An extreme eg. of this case is a clear, plastic, film, such as cellophane.

9. __________ utilizes the fact that the index of refraction of a material is a function of the wavelength of the light ray.
a) Absorption
b) Reflection
c) Refraction
d) Dispersion
Answer: d
Clarification: It’s the phenomenon in which the phase velocity of a wave depends on its frequency. The index of refraction of a material is often high for blue light than for the red one.

10. Light might also be ___________ as it is transmitted through a material. Reflection, refraction, and __________ of light are all very crucial in determining and predicting the optical properties of paper.
a) Absorption
b) Reflection
c) Refraction
d) Dispersion
Answer: a
Clarification: It’s employed as an analytical chemistry tool to calculate the presence of a particular substance in a sample and, in many cases, to quantify the amount of the substance which is present. Infrared and ultraviolet-visible spectroscopy are particularly common in analytical applications.

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Basic Pulp and Paper Questions and Answers on “Wood Chemistry”.

1. Cellulose is a material which can exist in crystalline and amorphous states
a) True
b) False
Answer: a
Clarification: It is a white solid material that exists in both the states. It is about 50 – 70% crystalline and forms the “back-bone” structure of wood fiber.

2. Which is the part where lignin is highly concentrated?
a) Outskirts of lamella
b) Middle lamella
c) Mitochondria
d) Pith
Answer: b
Clarification: Lignin is more highly concentrated in the middle lamella and primary cell wall regions of the wood fiber than any other part of cell wall.

3. Cellulose is a linear polymer of anhydro-D-glucose connected by beta-(1-4)-linkage?
a) True
b) False
Answer: a
Clarification: On the molecular level, cellulose is a linear polymer of anhydro-D-glucose connected by beta-(1-4)-linkage. The degree of freedom, which is the number of units (Glucose in this case) that make up polymer above 10,000 in unaltered wood.

4. What are the chemical elements present in wood?
a) C, O, H, N
b) Co₂, O₂, N₂, H₂
c) Co₂, O₂, N₂, H
d) Co₂, O₂, N, H₂
Answer: a
Clarification: The chemical components are carbon, oxygen, hydrogen, and nitrogen.
In the respective percentages 50%, 44.5%, 6.1%, and 0.5%.

5. Microfibrils occur in which section of cell wall?
a) Primary
b) Secondary
c) Tertiary
d) Quaternary
Answer: b
Clarification: Microfibrils are oriented in different directions in each of three layers within secondary cell wall.

6. ___________ decreases the strength of pulp yield, and are not ideal for dissolving pulp process.
a) Terpne
b) Hemicellulose
c) Lignin
d) Microfibrils
Answer: b
Clarification: Hemicellulose increase the strength of the paper and the pulp yield, especially tensile, burst, and fold.

7. Which of the following is a condensed polymer?
a) Microfibrils
b) Arabinogalactans
c) Hardwood hemicelluloses
d) Hemicellulose
Answer: d
Clarification: Hemicellulose are condensation polymers with a molecule of water removed with every linkage.

8. Which is the compound which is a complex polymer consisting of phenylpropane units and has an amorphous three-dimensional structure?
a) Extractives
b) Lignin
c) Terpenes
d) Hemicellulose
Answer: b
Clarification: Lignin is the compound which is a complex polymer consisting of phenylpropane units and has an amorphous three-dimensional structure. Its molecular weight in wood is very high and cannot be easily measured.

9. Which is the compound by definition are soluble in organic solvents, and water?
a) Extractives
b) Lignin
c) Terpenes
d) Hemicellulose
Answer: a
Clarification:Extractives are the compound of diverse nature with low to moderately high molecular weights, which by definition are soluble in organic solvents, and water. They impart colour, odor, taste, and ocassionaly, decay resisitance to wood.

10. Turpenes are made from _________ units in the living wood cell?
a) Sulphated isoprene
b) Phosphated isoprene
c) Carbonated isoprene
d) Hydrogenated isoprene
Answer: b
Clarification: Terpenes are a broad class of compounds appearing in relatively high quantities in the softwoods.

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Pulp and Paper Multiple Choice Questions on “Causticizing Process”.

1. What is a green liquor clarifier?
a) It is a settling tank used to remove dregs by evaporation
b) It is a settling tank used to remove dregs by condensation
c) It is a settling tank used to remove dregs by metamorphism
d) It is a settling tank used to remove dregs by sedimentation
Answer: d
Clarification: It’s a settling tank used to remove dregs by sedimentation before the green liquor is recausticized.

2. What’s a Slaker in Causticizing process?
a) It is a chemical reactor where lime is mixed with black liquor
b) It is a chemical reactor where lime is mixed with brown liquor
c) It is a chemical reactor where lime is mixed with green liquor
d) It is a chemical reactor where lime is mixed with red liquor
Answer: c
Clarification: It’s a chemical reactor where lime’s mixed with green liquor. The reaction temperature is 99-105 degree celcius.

3. Which of the following is a slaking reaction?
a) CaO+H₂Oandrarr;Ca(OH)₂
b) Na₂SO₄+4Candrarr;Na₂S+4CO
c) 2C+ O₂andrarr;2CO
d) CO+1/2 O₂andrarr;CO₂
Answer: a
Clarification: Slake formation takes place as calcium oxide is made to react with water to produce calcium hydroxide.

4. The lime kiln is a chemical reactor in which lime mud CaO, a process known as calcining.
a) True
b) False
Answer: a
Clarification: The lime kiln is a chemical reactor in which lime mud CaO, a process known as calcining.

5. What is the hidden part?
specific energy consumption=(energy to kiln)/(_________)
a) Ca output
b) CaO output
c) CO₂ output
d) CO output
Answer: b
Clarification: The amount of energy required to process the lime is indicated by the specific energy consumption, often reported as Btu/ton.

6. What is the hidden part?
Lime availability= (CaO)/(__________)
a) Caustic
b) Lime
c) Water
d) CO₂
Answer: b
Clarification: The purity of the lime is given by the lime available.

7. Salt cake is the make-up chemical for the Kraft process that is used to replace steams lost in pulping.
a) True
b) False
Answer: a
Clarification: Salt cake is the make-up chemical for the Kraft process that is used to replace chemicals lost in pulping.

8. __________ is the collection of waste N.S.S.C liquor and burning it in a nearby Kraft mill.
a) Cross over
b) Cross recovery
c) Bend over
d) Bend recovery
Answer: b
Clarification: Cross recovery is the collection of waste N.S.S.C liquor and burning it in a nearby Kraft mill.

9. ____________ oxides aren’t emitted to a large extent because the CaO is a good scavenger for the highly acidic forms of these compounds and CaSO3 and CaSo4.
a) Sulphur
b) Carbon
c) Calcium
d) Magnesium
Answer: a
Clarification: Supfur oxides aren’t emitted to a large extent because the CaO is a very good scavenger for the highly acidic forms of these compounds and CaSO₃
and CaSO₄
.

10. __________ formation within the lime kiln is a part of the territory and could be catastrophic?
a) Kink
b) Mask
c) Ring
d) Lumps
Answer: c
Clarification: Ring formation within the lime kiln is part of the territory. If it becomes a severe problem, expensive shutdowns may result.

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