Paper and Pulp
Class 12 Chemistry Notes • NEB Syllabus 2083
Syllabus, 10 solved multiple choice questions, all short and long answer questions with the flow sheet diagram, project work ideas, handwritten and typed PDF notes and frequently asked questions on paper and pulp.
1. Syllabus
Unit 20: Paper and Pulp
These notes follow the NEB Class 12 Chemistry syllabus (+2 Chemistry, Nepal). Practise the multiple choice questions first, then work through the solved numerical and subjective questions, and finish with the PDF notes for quick revision.
2. Multiple Choice Questions
Question 1. Which of the following is the primary raw material for paper production?
- a) Glass
- b) Wood
- c) Plastic
- d) Cotton
Correct Answer: b) Wood
Reason: Pulp, which is the primary raw material of paper, is made mainly from wood. Wood is rich in cellulose fibres, \(\mathrm{(C_6H_{10}O_5)_n}\). Glass and plastic have no fibres, and cotton is used only for high-quality special papers.
Question 2. What is the purpose of the pulping process in paper production?
- a) To shape the paper
- b) To make the paper glossy
- c) To add color to the paper
- d) To separate fibers from the wood
Correct Answer: d) To separate fibers from the wood
Reason: Pulping converts the wood chips into a soft fibrous mass. The lignin that binds the cellulose fibres is dissolved by chemicals (chemical pulping) or the wood is torn apart by machine (mechanical pulping), so the individual fibres are freed.
Question 3. Which type of paper is commonly used for writing and copying in schools and offices?
- a) Standard quality paper
- b) Specialty paper
- c) Newsprint
- d) High-quality paper
Correct Answer: a) Standard quality paper
Reason: Standard-quality paper is used for office printing and everyday use, such as books, workbooks and writing sheets. High-quality paper is for certificates and brochures, newsprint is low quality, and specialty paper is for tissue and wrapping.
Question 4. Which process is used to make paper brighter (whiter)?
- a) Sizing
- b) Chemical pulping
- c) Bleaching
- d) Mechanical pulping
Correct Answer: c) Bleaching
Reason: Bleaching with agents such as \(\mathrm{Cl_2}\), \(\mathrm{NaOCl}\) or \(\mathrm{H_2O_2}\) removes the remaining lignin and coloured substances from the pulp and so increases whiteness and brightness. Sizing controls ink absorption, and pulping only separates the fibres.
Question 5. What is the final step in paper production?
- a) Sizing
- b) Drying
- c) Pulping
- d) Pressing
Correct Answer: b) Drying
Reason: After the pulp is spread onto a moving screen to form a sheet, water is squeezed out by pressing and the remaining water is removed by drying on heated rollers. Drying is the last step of the forming, pressing and drying stage, after which the paper is only rolled, cut and packed.
Question 6. What type of paper is used for magazines and brochures?
- a) Premium
- b) Specialty paper
- c) Standard paper
- d) Low-quality paper
Correct Answer: a) Premium
Reason: Premium (high-quality) paper has a smooth, bright, polished surface that gives sharp print, so it is used for certificates, resumes, brochures and magazines.
Question 7. Which of the following is not commonly used as a raw material for making paper?
- a) Cotton
- b) Wood
- c) Rice husk
- d) Plastic
Correct Answer: d) Plastic
Reason: Paper is a mat of cellulose fibres from plants. Cotton rags, wood and agricultural residues such as rice straw supply these fibres. Plastic is a synthetic polymer and has no cellulose fibres.
Question 8. Which part of a tree is primarily used for paper production?
- a) Bark
- b) Flowers
- c) Wood
- d) Bark
Correct Answer: c) Wood
Reason: The wood of the trunk is chipped and pulped. The bark is removed in the debarking step because it contains impurities that affect the quality of paper. (Options a and d are the same in the textbook.)
Question 9. Which of the following is a non-wood material used for paper production?
- a) Pine
- b) Banana
- c) Eucalyptus
- d) Birch
Correct Answer: b) Banana
Reason: Pine is a softwood and eucalyptus and birch are hardwoods, all of which are wood. The banana plant gives non-wood fibre.
Question 10. Which fiber is commonly used for making high-quality paper?
- a) Hemp
- b) Bagasse
- c) Cotton
- d) Bamboo
Correct Answer: c) Cotton
Reason: Cotton rags give long, strong and almost pure cellulose fibres, which are used to make high-quality handmade paper.
3. Numerical and Subjective Questions
Short Answer Questions
a. Softwood is preferred over hardwood
Softwood trees such as pine and fir give long fibres (about 3 to 4 mm), while hardwoods such as eucalyptus and poplar give short fibres (about 1 mm). Long fibres interlock and bond better in the sheet, so the paper has more tensile strength and folding endurance. (Hardwood is used where smoothness and printability are needed.)
b. Lokta paper is preferred for official records
Lokta paper is made from the strong, durable and flexible bast fibres of the Daphne plant (Daphne bholua). It resists insects and decay and does not become brittle, so records such as birth certificates, government documents and religious texts last for a very long time.
Raw materials
The raw materials of paper production are of two types. Pulp, made of cellulose fibres from wood, recycled paper or other plants, is the main raw material; water and several chemicals are also needed.
| Raw materials | Examples | Function |
|---|---|---|
| Fibrous | Softwood, hardwood, bamboo, bagasse, straw, grasses, jute, cotton rags, Lokta, recycled paper | Supply the cellulose fibres that form the paper |
| Non-fibrous (inorganic) | Sodium hydroxide, alum, kaolin clay, calcium carbonate, titanium dioxide, \(\mathrm{Na_2S}\), \(\mathrm{Na_2CO_3}\), \(\mathrm{H_2O_2}\), \(\mathrm{Cl_2}\) | Break down lignin, size the paper, fill the pores, whiten |
| Non-fibrous (organic) | Starch, rosin, dyes, optical brightening agents, synthetic binders, glycerol, wax | Strength, water resistance, colour, brightness, flexibility |
Qualities of paper
The quality of paper (finish, absorbency, strength and brightness) decides how well it works for its use, and is influenced by:
According to these features paper is graded as:
| Grade | Use |
|---|---|
| Premium (high-quality) paper | Certificates, resumes, brochures, magazines |
| Standard-quality paper | Office printing, books, novels, workbooks, writing sheets |
| Low-quality paper | Newspapers, short-term materials, flyers |
| Specialty paper | Hygiene, delicate wrapping, decoration: tissue paper, wrapping paper |
| Nepali (Lokta) paper | Government offices, journals, crafts, packaging, traditional documents |
Fibrous raw materials
a. Paper and pulp
| Pulp | Paper |
|---|---|
| It is the soft, wet, fibrous raw material of cellulose fibres separated from wood or other plants and mixed with water. | It is the thin, flexible sheet, the final product. |
| It is the intermediate (raw material) in paper making. | It is made by forming the pulp on moving screens, pressing out the water and drying. |
| Fibres are loose in water. | Fibres are pressed together and dried into a sheet. |
b. Mechanical pulping and chemical pulping
| Mechanical pulping | Chemical pulping |
|---|---|
| Wood is physically shredded or ground into pulp by a machine. | Wood chips are cooked in a chemical solution to dissolve the lignin and get pulp. |
| No chemical or only a little chemical is used. | Chemicals are used (for example sodium hydroxide and sodium sulphide). |
| High yield of pulp. | Low yield of pulp. |
| Fibres are shorter and weaker. | Fibres are longer and stronger. |
| Paper is less durable (yellows with age because lignin remains); used for newsprint. | Paper is more durable; used for writing, packaging and premium papers. |
Non-fibrous raw materials
Non-fibrous materials are mixed with the pulp to give the paper the quality needed.
A. Inorganic raw materials
B. Organic raw materials
Stages
Flow sheet diagram
The flow sheet below shows the stages from timber to the finished paper.
Figure: Flow sheet diagram for the manufacture of paper
a. Bast fibres
b. Non-wood plants
a. Impact on the environment
b. Purpose of pulping
Lokta paper for records
Guidance for the project work
| Project | What to do |
|---|---|
| 1. Chart of paper industries of Nepal | Make columns for the name of the industry, location, specialty (writing and printing paper, packaging paper, tissue, handmade Lokta paper) and raw material used. Collect the names and locations of the industries from the internet or from your local market, and group them as large mills and handmade (cottage) Lokta paper industries. |
| 2. Poster of the stages of paper production | Draw one picture for each stage: timber, debarking, chipping and screening, pulping, bleaching and additives, forming, pressing and drying, and finished paper. Join them by arrows and copy the flow sheet diagram of this page in the centre. |
Figure: Flow sheet diagram for the manufacture of paper
Long Answer Questions
Stages and flow sheet
The manufacture of paper has the following stages:
Figure: Flow sheet diagram for the manufacture of paper
Raw materials for pulp
The main raw material of paper is pulp, made of cellulose fibres, \(\mathrm{(C_6H_{10}O_5)_n}\), from wood, recycled paper or other plants. Water and chemicals are also needed. The raw materials are of two types.
Fibrous raw materials. Softwood (pine, fir) gives long fibres and strength; hardwood (eucalyptus, poplar) gives short fibres, smoothness and printability. Bamboo is fast growing and gives strong long fibres. Bagasse is the waste of sugarcane. Straw and grasses (wheat, rice, kush, babiyo, reeds, siru) give short fibres. Jute gives long, strong, coarse fibres. Cotton rags give almost pure cellulose for high-quality handmade paper. Lokta gives strong durable bast fibres. Recycled paper gives already processed fibres.
Non-fibrous raw materials. Inorganic: sodium hydroxide (breaks down lignin), alum (sizing and pH control), kaolin clay (smoothness, brightness), calcium carbonate (whiteness and opacity), titanium dioxide (opacity), and other chemicals such as \(\mathrm{Na_2S}\), \(\mathrm{Na_2CO_3}\), \(\mathrm{H_2O_2}\) and \(\mathrm{Cl_2}\). Organic: starch (surface strength), rosin (water resistance), dyes and pigments (colour), optical brightening agents (whiteness), synthetic binders (strength), glycerol (flexibility) and wax (water resistance and coating).
Qualities of paper
Paper quality is the set of qualities (finish, absorbency, strength, brightness) that decides how well the paper does its job. It is influenced by the type of pulp (mechanical or chemical), paper weight and thickness (GSM), surface finish (glossy, matte, coated, uncoated), brightness and whiteness, and sizing (ink absorption and surface strength). Paper is graded as premium (certificates, resumes, brochures, magazines), standard (office printing, books, workbooks), low quality (newspaper, flyers), specialty (tissue and wrapping paper) and Nepali Lokta paper, a durable handmade paper used in government offices, journals, crafts, packaging and traditional documents.
4. View PDF Notes
i. Handwritten Notes
ii. Typed PDF Notes
5. Frequently Asked Questions
What are paper and pulp? (Paper and pulp class 12 notes)
What are the raw materials of paper and pulp?
What are the stages in the manufacture of paper? (Manufacture of paper and pulp)
What is the difference between mechanical pulping and chemical pulping?
Why is softwood preferred over hardwood, and why is Lokta paper used for records?
What are the qualities of paper?
What is the scope of the paper and pulp industry in Nepal? (Paper and pulp industry in Nepal)
How can paper production affect the environment?
Where can I get Paper and pulp pdf, Paper and pulp ppt and Paper and pulp class 12 notes pdf?
What topics are included in Unit 20 Paper and Pulp of NEB Class 12 Chemistry?
Where can I get Class 12 Chemistry notes of NEB (handwritten, PDF, Nepal)?
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