Grouping Materials

Q1. Define Material. and give few example.

Ans - Material is any thing made of matter, constituting one or more substances. Wood, cement, air, water and any other matter are all examples of materials.

Q2. Give reason - Grouping of material is important.

Ans - Organising or grouping things together makes our life simpler. It is easy to find things when they are properly arranged. Grouping various materials makes it easy to study them. Grouping help us to understand similarities and differences between various materials, hence grouping is important for us.

Q3. Describe properties of materials with examples, on basis of which they are classified.

Ans.

	Properties of material	Description of properties	Example
1	State	a)Solid -  definite volume and shape b)Liquid - definite volume but no shape c)Gas - don't have definite volume and shape	a)    Wood, Glass, Metal, etc b)    Water, Oil, Petrol, Milk, etc c)    oxygen, air, CNG, Carbondioxide, etc
2	Appearance i) Texture ii) Lustre	Texture - a) Smooth - plain and even surface b) Rough - bumpy and uneven surface Lusture - a) Shiny - material with shiny surface b) Dull - materials with rough or dull surface	Texture - a)    Paper, glass, flower petals etc b)    Wood, soil, rock, etc Lustre - a)    Metals, water, diamond, etc. b)    Rubber, wood, etc.
3	Hardness	a)     Hard - materials which are not compressed easily. b)    Soft - materials which are compressed easily	a)    Wood, Glass, Stone, Metals, etc b) Sponge, cotton, wax, etc.
4	Solubilty	a)     Soluble - solid that dissolve in water b)    Insoluble - solid that does not dissolve in water. c)     Miscible - Liquid that dissolve in water d)    Immiscible - Liquid that does not dissolve in water	a)    Salt, sugar, coffee powder, etc b)    Soil, metals, wood, etc. c)    Milk, vinegar, glycerine, etc d)    oil, kerosene, petrol, etc.
5	Floatation	a)     Float - things lighter than the water. b)    Sink - things heavier than the water	a)    Wood, wax, empty plastic bowl, etc b)    metals, stone, rubber, etc
6	Transparency	a)     Opaque - things that does not allow light to pass through them b)    Translucent - things that allow little light to pass through them c)     Transparent - things that allow light to pass through them	a)    wood, metal, wall,  etc b)    Paper, coloured glass, etc. c)    air, glass, etc.

Q4. How do large ships made up of metal float on water?

Ans. Metal ship  has full of air filled in its walls, so the average density of the ship as a whole become less than the density of water. Therefore immersed portion of the ship displaces water to its equal weight. so the ship floats.

Q5. Why do we use metals such as iron and stainless steel to make locks?

Ans. It is because of properties of metals i.e strongness and durability, we use them to make locks.

Q 6. Fishes cannot come out of the water. How they survive without oxygen, which is present in gas form in the air? Give one more example to justify your answer.

Ans - Some gases such as oxygen and carbon dioxide can be dissolved in waster in small amounts. The oxygen dissolved in seawater is used by aquatic animals and plants for survival. The carbon dioxide gas dissolved in fizzy drinks is observed as bubbles.

Q7. Glass is a transparent substance. How can we see our reflection in the mirror, if the mirror is made up of glass?

Ans -Mirrors are manufactured by applying a reflective silver coating to glass, due to its transparency, ease of fabrication, rigidity, hardness, and ability to take a smooth finish. This silver coating make transparent glass reflective.

Q8. Give reason: CNG is portable and easy to use.

Ans - CNG ( Compressed Natural Gas) is compressed to 1% of its original volume and filled in cylinders in this compressed form making it easy to use and portable.

Q9.Materials show more than one property. here are some things given below, identify the original material from which they are made up of and write its properties. Write one thing of your choice.

Ans.

no.	Things	Materials used	Properties
1	Curtains	cloth (cotton, silk)	solid, soft, shiny, smooth, translucent
2	Boat	wood, iron nails	solid, float, rough, hard, opaque, dull
3	Cupboard	wood, metal	solid, hard, opaque, Shiny metal
4	Fanta (fizzy drink)	water, CO2, sugar	liquid, translucent, miscible
5	Mango shake	milk, mango pulp, sugar	liquid, opaque, smooth, miscible
6	?	?	?