JK Academy Maharashtra Board Class 6 Science Solutions Chapter 6 Substances in Daily Use
Balbharti Maharashtra State Board Class 6 Science Solutions Chapter 6 Substances in Daily Use Notes, Textbook Exercise Important Questions and Answers.
Maharashtra State Board Class 6 Science Solutions Chapter 6 Substances in Daily Use
Class 6 Science Chapter 6 Substances in Daily Use Textbook Questions and Answers
Exercise
1. Fill in the blanks using proper words:
(a) Rubber made by
vulcanization is a …………… material.
Answer: hard
(b) Man-made
materials are made by …………… natural materials.
Answer: processing
(c) …………… thread
was developed simultaneously in New York and London.
Answer: Nylon
(d) Rayon is also known as …………….
Answer: synthetic silk
2. Answer the following questions.
(a) Why did the need for man-made materials arise?
Answer: The need for man-made materials arose due to the following reasons:
(i) to meet the needs of an increasing population.
(ii) to make life more comfortable.
(iii) it is human nature to strive for newer things.
(iv) several such substances are easier to use.
(v) can be made available in plenty at a low cost.
(vi) some man-made substances are water proof, lightweight and easy to transport.
(vii) the reserve of natural substances is decreasing.
(viii) to save our natural resources.
(b) Which are the natural materials obtained from plants and animals?
Answer: Leather, jute, wool, cotton, silk are the natural substances obtained from plants and animals.
(c) What is vulcanization?
Answer: Vulcanization is a process in which rubber is heated with sulphur for three to four hours. To give hardness to the rubber, sulphur is mixed in it. The proportion of sulphur in the mixture is determined by the purpose for which the rubber will be used.
(d) Which natural materials are used to obtain fibres?
Answer: Cotton, jute, fur of animals, wood pulp and various hydrocarbons obtained from mineral oils are used to obtain fibres.
3. What are we used for?
Answer:
(a) Soil – Soil supports all living things on Earth. It is also used to make various articles and as building material.
(b) Wood – Wood is used to make furniture, in paper industries and other decorative articles.
(c) Nylon – It is used for making clothes, ropes, fishing nets, etc.
(d) Paper – It is used as writing material, for packing and printing currency notes.
(e) Rubber – it is used for making rubber bands, erasers, toys, tyres, etc.
4. How is paper manufactured? Write in your own words.
Answer:
(i) Coniferous trees like pine are used to make paper.
(ii) The bark of the logs of these trees is first removed and the wood is broken into small pieces.
(iii) The mixture of these pieces and some chemicals is kept soaking for a long time. It helps to form pulp.
(iv) When the chemical process is completed, the fibrous substances from wood pulp are separated, and some dyes are added.
(v) The pulp is then passed through rollers, dried to form paper and finally wound on reels.
5. Give scientific reasons.
(a) We must use cotton clothes in summer.
Answer: Due to high temperature in summer, we sweat a lot. Cotton being a natural fiber, absorbs the sweat and keeps our skin dry.
(b) We must observe economy in the use of materials.
Answer: Due to the needs growing population, natural resources are getting depleted. It takes a very long time for these natural materials to get replenished. Therefore we must observe economy in the use of materials.
(c) Saving paper is the need of the hour.
Answer: Paper is made from trees. Tress are a natural habitat for many living things, they also help in increasing rainfall and preventing soil erosion. Trees take a long time to grow. Therefore we should save paper.
(d) Man-made materials have more demand.
Answer: Man made substances are easier to use and can be made available in plenty at a low cost. Therefore, these substances came to be used on a large scale and have more demand.
(e) Humus is a natural material.
Answer: When plants and animals die, they get mixed in the soil. Micro-organisms act on them and convert them to humus. Thus humus is a natural material.
6. Find out.
(1) How is lac obtained from nature?
Lac is a natural resin that is secreted by an insect, known as lac-insect. Lac insects live on the Palash trees. In order to obtain lac, these insects are cultured. It involves proper care of host plants, regular pruning of host plants, propagation, collection and processing of lac. In India lac is mainly produced in the states of Rajasthan and Bihar.
(2) How are pearls obtained?
Answer: Pearls are formed inside the shell of certain oysters as a defense mechanism against a potentially threatening irritant such as a parasite inside the shell, or an attack from outside that injures the mantle tissue. The oyster creates a pearl sac to seal off the irritation and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl.
Activity:
Visit a rubber, paper or textile industry in your area and collect information about it.
Collect various samples of paper and note their uses.
Use blank pages from old note-books and make a new one.