This set of Pulp and Paper Multiple Choice Questions and Answers (MCQs) focuses on “Bleaching Chemical Pulps”.
1. Cellulose viscosity of mechanical pulps and of high yield pulps are not measured since it’s quite low .
a) True
b) False
View Answer
Explanation: Cellulose viscosity of mechanical pulps and of high yield pulps are not measured since it’s quite high and not a factor in the strength properties of papers derived from these pulps.
2. Mechanical pulp bleaching is accomplished with various compounds containing Cl or O2 and alkali extractions in several stages.
a) True
b) False
View Answer
Explanation: Chemical pulp bleaching is accomplished with various compounds containing Cl or O2 and alkali extractions in several stages.
3. 2NaCl + 2 H2O + ____________ andrarr; Cl2 + 2NaOH + H2
a) Electricity
b) Heat
c) Acid
d) Alkali
View Answer
Explanation: Chlorine is not overly specific to lignin, and much carbohydrate degradation occurs through its use.
4. The ____________ stage is a modification of C stage bleaching, where some of the chlorine is replaced with ClO2.
a) AD
b) CD
c) FD
d) MD
View Answer
Explanation: The CD stage is a modification of C stage bleaching, where some of the chlorine is replaced with ClO2.
5. The ____________ is the process of extraction of degraded lignin compounds, which could increment the chemical usage in subsequent bleaching stages.
a) A stage
b) B stage
c) C stage
d) E stage
View Answer
Explanation: The E stage’s Extraction of de-graded lignin compounds, which could increment the chemical usage in subsequent bleaching stages.
6. Lignin-Cl + NaOH and rarr;Lignin-OH + NaCl
The lignin in the E effluent gives a ____________ colour that’s ultimately responsible for much of the colour of the final mill effluent.
a) Light
b) Dark
c) Transparent
d) Full black
View Answer
Explanation: The lignin in the E effluent gives a dark colour that is ultimately responsible for much of the colour of the final mill effluent.
7. ____________ and other chemicals are considered for bleaching stages, but don’t enjoy commercial importance.
a) Nitrogen oxides
b) Nitrogen peroxide
c) Nitrous hydroxide
d) Hydrogen
View Answer
Explanation: NO2 and other chemicals are considered for bleaching stages, but don’t enjoy commercial importance.
8. ____________ is a term used to describe each of 2 completely different methods. 1st is the utiliztion of enzymes which are isolated from decay fungi to selectively de-grade lignin.
a) Bio electric
b) Bio bleaching
c) Electrocuting
d) Bio degredation
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Explanation: Bio bleaching is a term used to describe each of 2 completely different methods. It’s akin to biopulping, and, like biopulping, is still only in the laboratory stages.
9. Bleaching with H2O2, is not common for chemical pulps. (But this is changing somewhat as mills look for chlorine-free systems.) It’s used for brightening mechanical pulps. What is the name of the alternative method utilized?
a) E stage
b) H stage
c) P stage
d) D stage
View Answer
Explanation: It’s utilized for brightening mechanical pulps, but when it’s used to bleach chemical pulps it appears as the last stage of a sequence such as C-E-H-P or C-E-H-D-P.
10. The ____________ is extraction of de-graded lignin compounds, which would increment the chemical usage in subsequent bleaching stages.
a) B stage
b) C stage
c) D stage
d) E stage
View Answer
Explanation: The E stag’s extraction of de-graded lignin compounds, which would increment the chemical usage.
Sanfoundry Global Education & Learning Series – Pulp and Paper.
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