chemistry

FIBRE TO FABRIC

Question: 1. Classify the following fibre as natural or synthetic.

Nylon, Wool, Cotton, Silk, Polyester and Jute

Answer- Nylon and polyester are synthetic fibre

.

Wool, cotton, silk and jute are natural fibre.

Question: 2. State whether the following statements are true or false.

(a) Yarn is made from fibre. (T)

(b) Spinning is a process of making fibre. (T)

(c) Jute is the outer covering of coconut. (F)

(d) The process of removing seed from cotton is called ginning. (T)

(e) Weaving of yarn makes a piece of fabric. (T)

(f) Silk fiber is obtained from the stem of a plant. (F)

(g) Polyester is a natural fiber. (T)

Question: 3. Fill in the blanks:

(a) Plant fibre are obtained from------ and------

Answer: - plants and animals.

(b) Animals fibre are-------- and -------

Answer: - wool and silk.

Question: 4 - From which parts of the plant cotton and jute are obtained?

Answer- Cotton is obtained from fruits of cotton plant and jute is obtained from stem of the jute plant.

Question: 5 - Name two items that are made from coconut fiber.

Answer: - Rope and doormats.

Question: 6 - Explain the process of making yarn from fiber.

Answer: Fiber is made from yarn by spinning. Spinning is done manually as well as using machines by twisting fiber; like rope making.

Extra Questions: -

Answer the following Questions: -

Questions: 1. Question- Which part of plants give us jute and coir?

Answer: Jute comes from the stem of jute plants, while coir comes from the husk of coconut fruit.

Questions: 2. Question- What is ginning?

Answer- The process of removing cotton seeds from cotton pods is called ginning.

Questions: 3. Question- What is spinning?

Answer- The process of making yarn from fibre is called spinning.

Questions: 4. Mention uses of jute fibre?

Answer- Jute is used mainly for making gunny bags, shopping bags, ropes, carpets, etc.

Questions: 5. Write the name of some manmade fibre?

Answer: Rayon, nylon, polyester, acrylic, etc.

Questions: 6. Write the name of animal fibre?

Answer- Silk and wool.

Questions: 7. What is caterpillar?

Answer: The larva of silk-moth is called caterpillar.

Questions: 8. Why do we need to wear clothes?

Answer- Clothes protect us from heat, cold and rain.

Multiple type questions: -

Questions: 1. Which of the following is obtained from natural sources?

(a) Wool

(b) Nylon

(c) Polyester

(d) Acrylic

Answer: - (a) Wool

Questions: 2. Which of the following is obtained from animals?

(a) Jute and cotton.

(b) Nylon and polyester

(c) Wool and silk

(d) Rayon and acrylic

Answer: - (c) Wool and Silk

Questions: 3. Silk worms are reared on which of these?

(a) On leaves of mulberry plant

(b) On the leaves of banyan plant

(c) On the leaves of spinach plant

(d) On the leaves of cotton plant

Answer: - (a) On leaves of mulberry plant

Questions: 4. Which of the following animals give wool?

(a) Sheep and yak

(b) Elephant and tiger

(c) Cow and dog

(d) Snake and duck

Answer: - (a) Sheep and yak

Questions: 5. Which of the following is obtained from hair of an animal?

(a) Silk

(b) Cotton

(c) Nylon

(d) Wool

Answer: - (d) Wool

Questions: 6. What is the name of process which involves pulling and twisting of strands of a fibre?

(a) Ginning

(b) Weaving

(c) Spinning

(d) None of these.

Answer: - (c) Spinning

Questions: 7. Which is the right time to cut jute plants?

(a) Flowering stage

(b) Mature stage

(c) Before flowering stage

(d) Any time after flowering.

Answer: - (a) Flowering stage

Questions: 8. Which part of the jute plant does give fibre?

(a) Root

(b) Stem

(c) Leaf

(d) Flower

Answer: - (b) Stem

SORTING MATERIALS INTO GROUPS

Question: 1. Name the objects which can be made from iron and wood.

Answer: Wooden items: window, door, sofa, chair, etc.

Iron items: Car, truck, bridge, utensil, grill, etc.

Question: 2. Select those objects from the following which shine.

Glass bowl, plastic toy, steel spoon, cotton shirt.

Answer: Glass bowl and steel spoon

Question: 3. Match the objects given below with the materials from which they could be made. Remember, an object could be made from more than one material and a given material could be used for making many objects.

Question: 4. State whether the statements given below are True or false.

(a) Stone is transparent, while glass is opaque. (F)

(b) A notebook has luster, while eraser does not. (F)

(c) Chalk dissolves in water. (F)

(d) A piece of wood floats on water. (T)

(e) Oil mixes with water. (F)

(f) Sand settles down in the water. (T)

(g) Vinegar dissolves in water. (T)

Question: 5. Given below are names of some objects and materials.

Water, basketball, orange, sugar, globe, apple and earthen pitcher.

Group them as:

(a) Round shaped and other shapes.

Answer: Round-shaped: Basketball, orange, globe and earthen pitcher.

(b) Eatables and non eatables

Answer: Eatables: Water, orange, sugar and apple.

Non-eatables: Basketball, globe and earthen pitcher.

Question: 6. List all items known to you that float on water. Check and see if they will float on an oil or kerosene.

Answer: Items; like wood, cork, Styrofoam, etc. float on water as well as on oil.

Question: 7. Find the odd one out from the following.

(a) Chair, bed, table, baby, cupboard

Answer: Baby is a living being, while others are non-living.

(b) Rose, jasmine, Boat, Marigold, Lotus.

Answer- Boat is a mode of transport, while others are flowers.

(c) Aluminium, iron, copper, silver, sand.

Answer: Sand is non-metal, while others are metals.

(d) Sugar, Salt, sand, copper sulphate.

Answer: Sand is insoluble in water, while others are soluble in water.

Extra Questions

Answer the following questions-

Question: 1. Name two materials which are soluble in water.

Answer- Sugar and salt.

Question: 2. Name two transparent and two opaque materials.

Answer- Glass, acrylic sheet are transparent materials, while stone and wood are opaque materials.

Question: 3. What are metals?

Answer- The substance which is hard, has luster and is good conductor of heat and electricity is called metal.

Question: 4. What is transparent material?

Answer: The material which allows light to pass through it is called transparent materials.

Multiple choice questions-

Question: 1. Which of the following is soluble in water?

(a) Sand

(b) Oil

(c) Glycerine

(d) Iron filing

Answer: - (c) Glycerine

Question: 2. Which of the following is insoluble in water?

(a) Chalk

(b) Washing soda

(c) Lemon juice

(d) Sugar

Answer: - (a) Chalk

Question: 3. Which of the following is a soft material?

(a) Iron

(b) Glass

(c) Dimond

(d) Chalk

Answer: - (d) Chalk

Question: 4. Which of the following is a hard material?

(a) Chalk

(b) Wool

(c) Cotton

(d) Diamond

Answer: - (d) Diamond

Question: 5. Which of the following can float on water?

(a) Iron pin

(b) Wood

(c) Steel

(d) Coin

Answer: - (b) Wood

Question: 6. Which of the following materials would sink in water?

(a) Steel spoon

(b) Piece of wood

(c) Pencil

(d) Toothbrush

Answer: - (a) Steel spoon

SEPERATION OF SUBSTANCES

Question: 1. Why do we need to separate different components of a mixture? Give two examples.

Answer- A mixture may contain one or more unwanted substances which may be harmful.

These impurities are harmful for our health so, we need to separate different components of a mixture. Examples: Pebbles are separated from rice and pulse. Petrol, diesel, kerosene, etc. are obtained from crude oil by a method called distillation.

Question: 2. What is winnowing? Where is it used?

Answer-The process of separation of grains from husk and hay with the help of wind is called winnowing. Farmers use this method for separating the grains from husk and hay.

Question: 3. How will you separate husk or dirt particles from a given sample of pulses before cooking?

Answer: For this, winnowing can be used.

Question: 4. What is sieving? Where is it used?

Answer-The process of separating solid constituents of different particle sizes; through a sieve is called sieving. Sieving is used while separating bran from flour. It is also used while separating pebbles from sand.

Question: 5. How will you separate sand and water from their mixture?

Answer- The mixture of sand and water can be separated by sedimentation and decantation.

Question: 6. Is it possible to separate sugar mixed with wheat flour? If yes, how will do it?

Answer: Yes, it is possible to separate sugar mixed with wheat flour. It can be done by the process of sieving.

Question: 7. How would you obtain clear water from a sample of muddy water?

Answer- We can get clear water from a sample of muddy water by the process of sedimentation, decantation and filtration. Coarser particles of soil would settle down at the bottom and partially clean water can be separated by decantation. The water thus obtained can be further clarified by filtration.

Question: 8. Fill in the blanks.

(a) The method of separating seeds of paddy from its stalks is called---------.

Answer- threshing

(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of -------

Answer- filtration

(c) Salt is obtained from sea water by the process of -------

Answer- evaporation

(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top.

The process of separations used in this example is called------------

Answer- sedimentation and decantation

Question: 9 - True or false?

(a) A mixture of milk and water can be separated by filtration. (F)

(b) A mixture of powdered salt and sugar can be separated by the process of winnowing. (F)

(c) Separation of sugar from tea can be done with filtration. (F)

(d) Grain and husk can be separated with the process of decantation. (F)

Question: 10 - Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add to the lemonade before or after dissolving sugar? In which case would it be possible to dissolve more sugar?

Answer: Ice should be added after dissolving the sugar. Saturation level increases with increase in temperature and vice-versa is also true. So, it is possible to dissolve more sugar in water at room temperature rather than at lesser temperature.

Additional Questions Based on Separation of Substances

Multiple Choice Questions

Question: 1. The process of settling down of particles of insoluble solid in a liquid is called

(a) Decantation

(b) sieving

(c) sedimentation

(d) winnowing

Answer- (c) sedimentation.

Question: 2. A solid substance is dissolved in water. Which of the following methods should be used for separating it?

(a) distillation

(b) evaporation

(c) decantation

(d) filtration

Answer- (b) evaporation

Question: 3. Which of the following properties of particles is ideal for winnowing?

(a) Difference in size

(b) difference in colour

(c) difference in weight

(d) difference in shape.

Answer: (c) difference in weight

Question: 4. Which of the following methods is used in separation of chaff from wheat?

(a) handpicking

(b) sieving

(c) Winnowing

(d) sublimation

Answer: (c) Winnowing

Question: 5. Which of the following methods is used in separation of pebbles from rice?

(a) sieving

(b) Winnowing

(c) sublimation

(d) Handpicking

Answer- (d) Handpicking

CHANGES AROUND US

1.Question.To walk through a waterlogged area,you usually shorten the length of your dress by folding it. can be reversed?

Answer. Yes. This change can be reversed.

2.Question. You accidentally dropped your favorite toy and broke it.Can this change reversed?

Answer.No. This change cannot be reversed.

3.Question. Some changed are listed in the following table.For each change, write in the blank column whether the change can be reversed or not?

Answer. Change------------------------ Can be reversed Yes\ No.   

 (1) The sawing of a piece of wood---   No

 (2) The melting of ice candy--------   Yes

 (3) Dissolving sugar in water-------   Yes

 (4) The cooking of food-------------   No

 (5) The ripening of a mango----------  No

 (6) Souring of milk-----------------    No

4.Question. A drawing sheet change when you draw a picture on it. Can you reverse this change?

Answer.If the picture is drawn a pencil, then it can be erased, hence change can be reversed.

But if picture is drawn with c lours, the change cannot be reversed.

5.Question.Give example to explain the difference between change that can or cannot be reversed.

Answer.Some changes can be reversed, like,

(1) Filling water with glass.

(2) Opening\Closing door.

Other change cannot be reversed, like,

(1) Cording of milk.

(2) Ripening of fruit.

6.Question. A thick coating of a paste of plaster of Paris (POP)is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured  bone immobilised. can the change in POP be reversed?

Answer.No. The change in POP cannot be reversed.

7.Question.A bag of cement lying in the open gets wet to rain during the night. the next day the sun shines brightly. Do you think the changes which have occurred in the cement could be reversed?

Answer. No. the changes which have occurred in the cement cannot be reversed

AIR AROUND US

1.Question. What is the composition of air?

Answer. Air contains some gases in air are mainly nitrogen,oxygen, small amounts of carbon dioxide, and many other gases.Air contains mostly nitrogen and oxygen. These two gases together make up 99% of the air. The remaining 1% is constituted by carbon dioxide and a few other gases, water vapour and dust particles.

2.Question. which gas in the atmosphere is essential for respiration ?

Answer. Oxygen.

3.Question. How will you prove that air support burning?

Answer. Two lighted candles are taken. one candle is covered a fixed in a tumbler containing water. This candle is covered by an inverted glass. After sometime, the covered candle gets extinguished and water rises upto 1/5th is oxygen. The candle extinguished as soon as all the oxygen was used up.                  

4.Question. How will you so that air is dissolved in water?

Answer.When a tumbler containing water heated, tiny bubles appear on the inner side. These bubles appear before the water starts boiling. So, these must be air bubles. This shows that water contains air.

5.Question. Why does a lump of cotton wool shrink in water?

Answer.a lump of cotton wool shrink in waterbecause the air inside wool cotton is driven out by water. They layer stic together and hence the lump shrinks.

6.Question. The layer of  air around the earth is known as:-

Answer.atmosphere.

           

                

7.Question. The comppnent of used by green plants to make their food, is :

Answer. Carbon doxide.

8.question. List five activities that are possible due to the presenmce of air.

Answer. (1) Winnowing.

              (2) Formation of clouds.

              (3) Respiration.

              (4) Photosynthesis.

             (5) Transpiration.

             (6) Flying of birds.