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Ncert Exemplar Solutions Class 7 Science Fibre to Fabric
Welcome to NCTB Solutions. Here with this post we are going to help 7th class students for the Solutions of NCERT Exemplar Class 7 Science Book, Unit 3, Fibre to Fabric. Here students can easily find step by step solutions of all the problems for Fibre to Fabric, Also here our Science teacher’s are solved all the questions with easily understandable language with proper guidance so that all the students can understand easily.
Fibre to Fabric Solution :
Multiple Choice Questions :
Question no – (1)
The rearing of silkworms for obtaining silk is called
Answer :
The correct answer is option – (c)
The rearing of silkworms for obtaining silk is called Sericulture.
Question no – (2)
Which of the following is not a type of silk?
Answer :
The correct answer is alternative – (d)
Moth silk is not a type of silk.
Question no – (3)
Paheli wanted to buy a gift made of animal fibre obtained without killing the animal. Which of the following would be the right gift for her to buy?
Answer :
The correct answer is option – (a)
Woollen shawl will be the right gift for her to buy.
Question no – (4)
Silk fibre is obtained from
Answer :
The appropriate option is – (c)
Silk fibre is obtained from Cocoon.
Question no – (5)
Wool fibre cannot be obtained from which of the following?
Answer :
The correct answer is option – (d)
Wool fibre cannot be obtained from Moth.
Question no – (6)
Selective breeding is a process of
Answer :
The correct option is – (b)
Selective breeding is a process of selecting the parents with desired properties.
Question no – (7)
The general process that takes place at a sheep shearing shed is
Answer :
The correct answer is option – (a)
The general process that takes place at a sheep shearing shed is removal of fleece.
Question no – (8)
Answer :
The correct answer is alternative – (b)
The term sericulture is used for rearing of silkworm.
Question no – (9)
Reeling of silk is
Answer :
The correct option is – (d)
Reeling of silk is the process of taking silk threads from cocoon.
Question no – (10)
Silkworms secrete fibre made of
Answer :
The correct answer is option – (c)
Silkworms secrete fibre made of Protein.
Very Short Answer Questions :
Question no – (11)
Answer :
(a) Silk and wool fibres are obtained from animals.
(b) Silk fibres come from cocoons of silk moth
(c) Wool yielding animals bear Hair on their body.
(d) Hair trap a lot of air, which is a poor conductor of heat
Question no – (12)
Answer :
(a) Silkworms are caterpillars of silk moth
This statement is True.
(b) In India, camels and goats are generally reared for obtaining wool
This statement is False.
Reason : In India sheep are generally reared for obtaining wool.
(c) The rearing of silkworms for obtaining silk is called silviculture
This statement is False.
Because, The rearing of Silkworms for obtaining silk is know as sericulture.
(d) In the process of obtaining wool from fleece, sorting is done after scouring
This statement is True.
(e) Yak hair are not used to make woollen fabric.
This statement is False.
Because, Yak hairs are used to make woolen fabrics.
Question no – (13)
Answer :
The hair on certain animals traps air which is a very bad conductor on heat, so the air prevents the body heat to escape thus keeping the animal warm.
Short Answer Questions :
Question no – (14)
Answer :
(a) → (iii) Tibet and Ladakh.
(b) → (iv) Jammu and Kashmir.
(c) → (ii) Silkworm.
(d) → (i) Sheared hair.
Question no – (15)
Answer :
The correct sequence is –
(iii) Shearing.
↓
(iv) Scouring.
↓
(v) Sorting.
↓
(i) Picking out the burrs.
↓
(ii) Dyeing in various colours.
Question no – (16)
Answer :
(a) TURECULRISE → Sericulture.
(b) WILSMORK → Silkworms.
(c) BELMURRY → Mulberry.
(d) RINGLEE → Reeling.
Question no – (19)
Answer :
Correct Sequence is as follows :
(E) → Female silk moth lay eggs.
(A) → Eggs are warmed to a suitable temperature for the larvae to hatch from eggs
(D) → The larvae/ caterpillar or Silkworms are kept in clean trays along with freshly chopped mulberry leaves.
(C) → After 25 to 30 days, the caterpillars stop eating and start spinning cocoons.
(F) → Cocoons are kept under the sun or boiled in water.
(B) → Fibers are taken out from the cocoon.
Question no – (20)
Answer :
(a) → (iii) Kasmir goat.
(b) → (i) Camel wool.
(c) → (ii) Angora wool.
(d) → (iv) Sheep wool.
Long Answer Questions :
Question no – (21)
Answer :
The Female silk moth lays Eggs, from which hatch Larvae called Caterpillar or Silkworms. They grow in size and when the caterpillar is ready to enter the next stage of its life history called Pupa, it first weaves a covering to hold itself, which is known as Cocoons.
Question no – (22)
Answer :
The saree whose thread burnt with the smell of a burning hair is silk as we know that silk and hair are both made from protein fibres which emits the same kind of smell. While on the other hand the saree whose thread burnt with the smell of a burning paper is pure cotton as we know that cotton and paper both contain carbohydrates which while burning emit the same kind of smell.
Question no – (23)
Answer :
The phrase “Unity in Strength” is self explanatory. A single length of fibre is too weak or fragile, it could be easily torn apart. But when the same fibres are spun into yarn and then weaved into fabrics. The fabrics becomes so much strong it becomes difficult to tear apart the fabric.
Question no – (24)
Answer :
The various steps for processing fibres into wool are –
• Shearing– The hair of the sheep along with some skin is removed from its body by using a machine
• Scouring– The sheared hair is then washed in tanks to remove potential dust, dirt or grease.
• Sorting– In the factory the hairy skin is separated into different textures.
• Then the burrs or small fluffy are separated from the hairs to be washed again and dried.
• It is then dyed with different colours.
• The fibers are straightened, combed and rolled into yarns to be later spun and woven into fabric.
Question no – (25)
Answer :
At first the female silk moth lays some eggs on the leaves of the mulberry tree. The eggs then hatch to form larvae often called Caterpillars or Silkworms. These larvae then feeds on the leaves and grow in size. If the larvae becomes ready to enter the next stage of its life called pupa it secretes silk fibers to form a hard covering for itself which is known as a cocoon.
Long Answer Questions :
Question no – (26)
Answer :
China rose is a natural indicator so when the solution A was added it turned pink as the solution was acidic in nature, just like that when solution B was added to it turned green and since no colour change was observed when solution C was added it means that it was neutral in nature.
Question no – (27)
Answer :
If the farmer finds out the soil is acidic he must treat the soil by adding bases like quick lime( calcium oxide) or slaked lime( calcium hydroxide) which neutralizes the soil. But if the soil is too basic organic matter like compost should be added as it releases acids which neutralizes the acidity of the soil.
Question no – (28)
Answer :
In order to the nature of the solution we can taste the solutions, so if the solutions taste sour it will be basic or if it taste bitter then it’s basic but if it’s taste other than sour or basic then it’s neutral. The tamarind solution taste sour so it’s acidic. The baking soda solution taste bitter so it’s basic. While the sugar and salt solutions taste sweet and salty so they are neutral in nature.
Question no – (29)
Answer :
(a) a piece of blue litmus paper in each test tube.
= When blue litmus paper is added to solution A it turns red, but it remains blue in solution B and C.
(b) a piece of red litmus paper in each test tube.
= When red litmus is added to solution A and C it remains red ,but in solution B it changes to blue.
(c) a few drops of phenolphthalein solution to each test tube.
= When phenolphthalein drops are added to solution A and C no colour changes are observed while solution B changes to pink.
Question no – (30)
Answer :
(a) The water is contaminated by the acidic or basic waste which is released by the factory in the water. This makes the water inhabitable for the fishes and eventually kills them.
(b) If the factory waste is acidic in nature it’s harmful effects can be neutralized by adding basic substances such as quick lime or slaked lime.
Question no – (30)
Answer :
The two neutralization effects related to daily life situations are –
• Indigestion: When our stomach has too much acids it causes indigestion which if often treated by antacid such as milk of magnesia which neutralizes the acid.
• Ant bite :When a person is stung by a bee, it releases an acid in the person. The effects of the acid can be neutralized by rubbing moist baking soda or calamine solution over the infected area.
Other Chapter Solutions :
👉 Heat
👉 Physical and Chemical Changes
👉 Weather, Climate and Adaptation of Animals to Climate
👉 Soil
👉 Transportation in Animals and Plants
👉 Electric Current and Its Effects
👉 Light
👉 Wastewater Story
