8th Synthetic fiber and plastic

Q. Why do we wear clothes?

Ans: We wear clothes for protection against climate and to look smart. Fabric is the material that is used to make clothing or household articles.

Q. Of what material fabrics are made of?

Ans: Fabrics are made up of smaller threads or hair like structure. single hair like structure  is called a fibre. Short fibres are called  Staple fibre . Long fibers are called   Filament fibre

Q. What is natural fibre?

Ans: Fibers obtained from natural sources like plants and animals is called natural fibre. e.g. cotton, Jute, silk, wool, etc

(i)Vegetable Fibres: fibres which are obtained from different plants are called Vegetable Fibres.  For example Cotton is obtained from seed of the plant, jute is obtained from the stem of a plant and coir is the outer covering of coconut

(ii) Animal Fibres: fibres which are obtained from different animal sources is called a Animal Fibres eg sheep goat, rabbits ,camels and silk worm..

Q. What are man-made fibers?

Ans:  Fibres  that are obtained from chemical substance are called manmade fibres. E.g. rayon, polyester, nylon, acrylic (cashmilon)   etc. The first man-made fibre is known as rayon.

Q. State whether the following are true or false and correct the false statements:

(i) Fibre is the basic unit of all fabrics.      (T)                        
 (ii) Filament are short fibres.(F)

(iii) Jute is the outer covering of coconut.(F)                       
(iv) Silk is prepared from the stem of a plant.(F)

(v) Polyester is a staple fibre. (F)

Q. How you distinguish natural fibre and synthetic fibre?

Ans :  BURNING TEST  helps to identify fibers.

COTTON AND RAYON	Catches fire easily	burn with a bright yellow flame	ash
SILK AND WOOL	Does not catch fire easily	Do not burn with a bright yellow flame	Black crushable bead
NYLON, ACRYLIC	Does not catch fire . melts flame  Shrinks away from No definite smell Hard,	Shrinks away from flame. Burns with

 Q. How yarn is made?

Ans: A yarns is a continuous strand made up of a number of fibers which are twisted together.

The process of making yarns from fibres is called spinning. Here the fibres are not only twisted but also pulled out or drawn.

Spinning can be done by using a takli (spindle), a charkha or a spinning machine

Q. State whether the following are true or false:

(i) Yarn is made of a number of fibres.

(ii) Staple fibres are used to make a yarn.

(iii) Spinning is a process of making fibres.

(iv) Spinning increases the strength of yarns.

(v) Twisting increases the strength of the yarns.

(vi) Smoothness of a yarn depends on the twisting of the fibres.

(vii) Blends are made from different fibres.

Q. Define weaving?

Ans: Weaving is the process of interlacing two sets of yarns at right angles to each other to make a fabric.

Weaving is done on looms. Hand operated looms are called handlooms and power operated ones are called power looms. Knitting is interlooping of one or more set of yarns

More help on : Synthetic Fibre And Plastics

VIII Synthetic fiber and Plastic
Read and download
VIII Synthetic fiber and Plastic
Read and download
8th Synthetic fiber and Plastic [Solved Questions]
Download File


Terms related to synthetic materials
types of synthetic materials , synthetic materials list,synthetic materials examples, synthetic materials definition , natural materials, synthetic materials examples list, polyester, synthetic materials journal

Searches related to synthetic materials class 8

synthetic fibres and plastics for class 8

class 8 corrosive materials

class 8 hazardous material

study material for class 8

synthetic fibres and plastics class 8 ppt

synthetic fibres and plastics class 8 extra questions

synthetic fibres and plastics class 8 mcq
synthetic fibres and plastics class 8 videos

7th Acids bases and Salts [Solved]

CBSE Solved Questions For Students of Central public School and Sadhana Devi Vidyapith 

Q1. What are acids?

Ans. Acids are the substances which are sour in taste.

Q2. What are bases?

Ans. Bases are the substances which are bitter in taste & soapy to touch.

Q3.Give examples of acids and bases.

Ans. Acids- hydrochloric acid, acetic acid, citric acid, lactic acid etc

Bases- baking soda, sodium hydroxide, soap etc

Q 4. Name the acids present in the following substances.

Substance	Acid
Vinegar	acetic acid
Curd	lactic acid
Guava	oxalic acid
Lemon	citric acid
Amla	citric acid
Tamarind	tartaric acid

Q5. What are indicators? Give examples.

Ans. Indicators are the special type of substances which are used to distinguish between acids & bases by showing colour changes.

Example: litmus, turmeric, beetroot, China rose extract, phenolphthalein etc.

Q6.Name the source from which litmus is obtained.

Ans. Litmus is obtained from a plant lichens.

Q7. in what forms is litmus available?

Ans. Litmus is available in the form of solution or in the form of strip of paper.

It is available as red & blue litmus.

Q8. Why do we use indicators?

Ans. We use indicators to find out whether a substance is acidic, basic or neutral, as all the substances can’t be tasted. Some of the substances are highly corrosive and hence can be harmful to us if tasted.

Q9.What happens when phenolphthalein is added to  (a) Acidic solution (b) basic solution (c) Neutral solution

Ans.
(a) in acidic solution, the colour of phenolphthalein remains colourless.

b) When phenolphthalein is added to basic solution, the colour changes to pink (magenta).

c) In neutral solution, it remains colourless.

Q10.What are neutral substances?

Ans. The substances which are neither acidic nor neutral are known as neutral solutions.

Q11. What happens when a base is put on turmeric paste? What will happen when acid is added to the same?

Ans. When base is added to turmeric paste, then its colour changes to red. If we put an acid on the same then changes to yellow again.

Q12. How will you identify weather a substance is acidic or basic using red & blue litmus?

Ans. Acids & bases can be distinguished using litmus solutions as follows:

- if the colour of red litmus changes to blue, then the substance is basic in nature.

- if the colour of blue litmus changes to red, then the substance is acidic in nature.

Q13. Ammonia is used in many household products like window cleaners. It turns red litmus to blue. What is the nature of ammonia?

Ans. As ammonia turns red litmus to blue that shows it is basic in nature.

Q14. What is the effect of China rose indicator on acidic & basic solutions?

Ans. China rose indicator turns acidic solutions to dark pink and basic solutions to green.

Q15.What is neutralization reactions?

Ans. The reaction in which an acid & a base react to form salt and water, with the evolution of heat is known as neutralization reaction.

Acid + base ------> salt + water.

Hydrochloric acid + sodium hydroxide --> sodium chloride + water

Q16. What are salts? Are they acidic, basic or neutral?

Ans. Salts are substances formed by the reaction of an acid and base. Salts can be acidic, basic or neutral.

Q17. What are antacids?

Ans. antacids are the medicines that arte use to relieve from acidity in stomach. Example: milk of magnesia, eno etc.

Q18 what causes acidity in stomach?

Ans. Our stomach contains hydrochloric acid which helps us to digest food. When the amount of acid present in stomach increases, it leads to acidity.

Q19 How is antacids helpful in relieving indigestion?

Ans. Antacids are basic in nature, hence they neutralize the effect of excess of acid and relieve us from indigestion.

Q20. Why is calamine solution put on the ant sting?

Ans. When an ant bites, it injects formic acid into the skin. The effect of acid can be neutralized by applying calamine solution which is basic in nature.

Q21.Sometimes we treat the soil with bases. Give reasons why?

Ans. Excessive use of fertilizers makes the soil acidic, which is not suitable for the growth of the plants .Hence we treat the soil with bases like calcium oxide to neutralize of acid.

Q22.The factory waste is treated with basic substances before disposing it?

Ans. The wastes of factories contain acids. If they are allowed to flow into the water bodies, then they are harmful to the aquatic life. Therefore, factory waste are treated with basic solutions.

Q23.What is the chemical name of the following:

Common name	Chemical name
Quick lime	Calcium oxide
Slaked lime	calcium hydroxide
Baking soda	sodium hydrogen carbonate

Q24. What is the chemical composition of milk of magnesia?

Ans. The chemical composition of milk of magnesia is magnesium hydroxide.

Q25. What is the chemical composition of calamine solution?

Ans. The chemical composition of calamine solution is zinc carbonate.

Related study materials

MCQ:Acid base and salt: For Olympiads-1 

Download File    
MCQ:Acid base and salt: For Olympiads-2
Download File 

7th Forest products and Waste management [Science class VII]

Holy faith abc of Science

I. Long answer type question

1. What are different ways of solid waste disposal?      

Ans : Following are different ways of solid waste disposal

(a)Solid waste is burnt and ash is removed from time to time

(b)Solid waste is buried in low lying area to level uneven ground

(c) Domestic solid waste are buried in a pit to make compost

(d)Non biodegradable solid wastes are recycled and reused

2. Why are forests such a valuable resources?

Ans: Forest product play vital role in socio-economic development. We get food (cereals, pulses, fruits), firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and products of medicinal importance.  It is also the home of diverse wildlife which maintains the ecosystem. Thus forests are valuable resources.

 3. List the various ways in which we can conserve forest?           

Ans: The various ways in which we can conserve forest are:

(i)Deforestation should be compensated by Afforestation.

(ii) Discourage the uses of firewood

(iii)By controlling forest fire applying anti-fire solution

(iv)Controlling overgrazing

(v) Educating people about the importance of forest.

4. List some uses of forest?

Ans: some uses of forest are:

(i) Forest purifies air and prevent air pollution

(ii)Forests recycle water into atmosphere

(iii) Forest bind soil and prevent soil erosion.

(iv) Forest gives us food, timber and medicinal materials

5. What are the techniques of waste management?

Ans: Following are the techniques of waste management

(i) Reduce consumption or find its substitute

(ii)Try to reuse it again and again in other form

(iii) Recover material for recycling

(iv)  Produce energy from the waste,

 II. Short answer type questions

1. How can an individual contribute in improving the quality of life?

Ans: An individual can contribute in improving the quality of life by :

(i)By thinking globally and act personally.

(ii) Joining hand with other to sustain and heal the earth.

(iii) By learning the how nature we are dependent on each other.

(iii) By giving protection and respect to every organism

2. List some problem caused by deforestation?

Ans: (i) Ecosystem and the ecological balance get disturbed.(ii)There is increase in global warming

(iii)Soil erosion will increases

(iv) Wild life may  not survive for long time.  

3 . What is waste management?

Ans: Waste management is the process of collection, transportation and disposal of waste materials.                                                                                                                                   

4. How is sea wage treated?  

Ans:   Treatment of sewage includes removal of solid waste from sewage and making liquid part less harmful.  In sewage treatment plant at first large solid material are removed by passing through vertical bars.  Now Liquid waste left is made to pass settling tank small sized solid impurities live sand or gravel are removed. After this, water is sent to sedimentation tank to separate organic waste. At last left water is chlorinated before releasing into water bodies.
5. How plants and animal interdependent?

Ans: Plants produce food using co₂ given by animals where as oxygen given by plant is used by animals. Animal help plant in pollination and dispersal of seeds and plant provide valuable food and medicinal product. Plants give shelter for animals where as animals excreta provide mineral for growth. Thus we can say that plants and animal interdependent.

III. Very short answer type questions

1. What is food chain?

Ans: A Food chain is a series of organisms depending on next one to feed upon.

2. What do you mean by planed harvesting of forest?

Ans: Use of modern management system that ensures that forest values will be protected during harvesting is called planed harvesting.

3.”You conserve forest, you conserve soil” Justify this statements.

Ans: Forests bind soil with roots and prevent soil erosion. They maintain fertility of soil and check flood.

4. Which should be bigger: those used for sea wage disposal or those used for storm water disposal?

Ans: storm water disposal            

5. Write short notes on: (a)Industrial effluent  (b) Sewage treatments (c) Forest conservation (d)Rainwater harvesting

Ans:

(a)Industrial effluent: The water discharged by the industries into drains and river that causes water pollution is called Industrial effluent.

(b) Sewage treatments: Treatment of sewage includes removal of solid waste from sewage and making liquid part less harmful is called Sewage treatments .  

 (c) Forest conservation: Management, protection and wise use of forest resources is called Forest conservation.

(d) Rainwater harvesting: The practice of storing rain water for further use is called rainwater harvesting. 
6. Distinguish between- (a) flora and fauna (b) tropical evergreen forest and deciduous forest.

(c) Thorn forest and mangrove forest.

Ans: (a) Flora and fauna is the term given to the plant life and animal life respectively. Their interactions comprise the ecosystem and the biodiversity on the planet earth. Hence, they are obviously inter-related.

(b)An temperate evergreen forest is a forest consisting entirely or mainly of evergreen trees that retain green foliage all year round. Deciduous trees lose their leaves in fall. The natural decaying of the fallen leaves enriches the soil and supports all kinds of plant and animal life.

 (c)The thorn forests are found in the region getting rainfall less than 70 cm . Mangrove Forests are found in the delta regions. The trees in the mangrove forests have roots completely submerged in water. They are dense and provide hard and durable timber

7. What are crown and Canopy?       

Ans: The part of the tree with branches is known as the crown. When the crown of tall trees in the forests forms a roof-like covering over the other plants, it is known as a canopy.

8. What is desertification?

Ans: The process by which fertile land becomes desert, due to drought, deforestation, or inappropriate agriculture is called desertification.

IV. Fill in the blanks

(a)The loss of ------- is the greatest threat of wildlife. [Forest]

(b)Sea water is unfit for ------------- purpose. [domestic]

(c) Waste is a material having no ------------ utility. [further]

(d)The sewage systems were ------- type in olden days.[three]

(e)Discharge of waste water from industries is known as ------------- [Industrial effluent]

NCERT/CBSE -7th Science Assignment Chapter –Waste Water Story

Q1) Fill in the blanks:-

(a) The World Water Day is on __________.

(b) The activated sludge is about __________ water.

(c) Water is disinfected by using chemicals like __________ and __________.

(d) __________ and __________ are water borne diseases

(e)The sewage system were ------ type in olden days.

Q2) What is sewage? What does it contain?

Q3) Give two examples of organic and inorganic impurities present in sewage.

Q4) What is meant by waste water?

Q5) How many processes are involved in the treatment of waste water? Name them.

Q6) What is the function of the bar screen used in a Wastewater Treatment Plant?

Q7) What is sludge?

Q8) What is clarified water? Explain.

Q9) What is the difference between aerobic and anaerobic bacteria?

Q10) Give reasons

a. Eucalyptus trees are grown all along sewage ponds.

b. Used tea leaves, solid food remains, cotton etc. should be thrown in the dustbin.

c. Large amount of waste generated at public places must be disposed off properly.

d. Untreated human excreta is a health hazard.

Ans:

a) Eucalyptus trees are grown near sewage ponds as they can grow in contaminated soils and soil containing high amount of salt and organic matter. Also, they absorb the metals, organic matter, nutrients and water from the sewage.

b) These wastes choke the drains. They do not allow free flow of oxygen. This hampers the degradation process.

c) Large amount of waste generated at public places must be disposed off properly otherwise epidemics could break out. 

d) Since a very large fraction of our people defecates in the open, on dry riverbeds, on railway tracks, near fields and many a time directly in water.It may cause water pollution and soil pollution

Q11) Write a short note on “vermiprocessing toilet”.


Q12) What can we do to reduce the load of pollutants in waste water and the pressure on Wastewater Treatment Plant?


Q13) Each tree can make its own manure. How?


Q14) How is sea wage treated?


Q15) What are the technique of waste water managements?


CBSE 7th Waste Water Story management Solved Test Paper Click here


CBSE 7th Waste Water Story management Solved questionsr Click here

MCQ: Fill in the blanks: Acid base and salt d salt

MCQ	Fill in the blanks:  Acid base and salt d salt
1.	The substances whose aqueous solution change the blue litmus to red ------------------Acids
2.	The substances having a tendency to lose one or more protons are called: ------------   Acids
3.	The substances which donate the pair of electrons for bond formation, are known as:-------     Base
4.	When equivalent quantities of acid and base are mixed, salt and water are formed, the reaction is termed as:----------- Neutralization
5.	The acids which contain one acidic hydrogen are called:-------- Mono-protic
6.	The number of acidic hydrogen atoms present in a molecule of an acid is called: ----  Basicity
7.	The number of replaceable [OH] ions present in a molecule of base, is called: ---    Acidity
8.	An acid that produces large number of (H) ions in aqueous solution is called: ---------Strong acid
9.	An ionic compound, that is formed when an acid neutralizes a base, is called:------ Salt
10.	SaIts that formed by the reaction of strong acid with weak base are:----Acidic
11.	Alums are example of  ---------salt:               Double salts
12.	The formula of Washing Soda is                                                  Na₂CO₃ 6H₂O
13.	Acids are the substances which give H+ ions aqueous solution, is the concept of:   Arrhenius
14.	Arrehenius theory of acid-base is not applicable in:     non — aqueous solution
15.	According to the Arrhenius concept, the strength of acid or base is based on their:   -------- a. rates of ionization          b. rates of dissociation
16	According to Bronsted — Lowry concept, a base is a substance which acts as:      a proton acceptor(NH₃)

CBSE ADDA: Chemistry:MCQ:Acid base and salt: For Olympiads

Multiple-Choice Questions: Acid base and salt

1.  The word acid comes from the Latin word ‘ acere ‘ which means

a)      Sweet

b)      Salty

c)      Neutral

d)      Sour

2. Substances which are bitter in taste, feel soapy on touching are known as

a)      Acids

b)      Bases

c)      Indicators

d)      Neutral solution

3. Special type of substances used to test whether a substance is acidic/basic are known as

a)      Indicators

b)      Acids

c)      Bases

d)      Salt

4. Some naturally occurring indicators are

(a). Turmeric

(b)  Litmus

©. China rose

(d). All the above

5.The most commonly used natural indicator’ Litmus’ is extracted from

(a).Lichens

(b). Turmeric

©. Indicators

(d). China rose

6. Litmus is available in the form of

(a). Litmus paper

(b) Lichens

©   Indicator

(d). China rose

7. Neutral solutions which do not change the colour of either red/blue litmus are known  as

(a).Neutral solutions

(b) Acid solutions

©. Basic solutions

(d). Neither acidic nor basic

8. Acetic acid is found in

(a).Curd

(b). Spinach

©  Citrus fruits

(d). Vinegar

9. Formic acid is found in

a). Curd

(b). Spinach

©. Ant’s sting

(d) Ascorbic acid

10. Citric acid is found in

(a). Curd

(b). Citrus fruits

©. Ascorbic acid

(d). Lime water

11. Lactic acid is found in

(a). Curd

(b).Citrus fruits

©.Gooseberry

(d)Lime

12. Oxalic acid is found in

a)      Spinach

b)      Curd

c)      Oranges

d)      Unripe mangoes

13. Ascorbic acid is found in

(a). Amla & Citrus fruits

(b) Curd

©.  Oranges & lemon

(d).Unripe mangoes

14. Tartaric acid is found in

(a). Tamarind

(b) Grapes

©  unripe mangoes

(d)All of the above

15. Calcium hydroxide is found in

Calcium carbonate

Calcium chloride

Calcium

Lime water

16. Ammonium hydroxide is found

(a).Window cleaner

(b).Detergents

(c)  Soap

(d). Milk of magnesia

17. Sodium hydroxide is found in

a)      Soap

b)      Window cleaner

c)      Calcium hydroxide

d)      Sodium

18. Potassium hydroxide is found in

(a). Soap

(b). Window cleaner

© Potassium

(d)Potassium chlorate

19. Magnesium hydroxide is found in

(a). Milk of magnesia

(b).Magnesium chloride

(c)  Magnesium ribbon

(d) Magnesium hydroxide

20.Which of the following salts is basic in nature?

(a) NH4NO3

(b) Na2CO3

(c) Na2SO4

(d) NaCl

Answer

1. D         2  b          3. A              4. D            5. A            6. A          7. A        8. d

9. C           10. b      11. A          12. A          13. A           14.  D         15. d         16. A

17. A      18. A             19.a         20 B