(i) Three layers of the earth are:
Crust (outermost layer), Mantle (middle layer) and core (innermost layer)
(ii) Any natural mass of minerals matter which makes up the earth’s crust is known as rock. Rocks can be of different colour, size and texture.
(iii) There are three types of rocks:
- Igneous rock of primary rocks
- Sedimentary rock
- Metamorphic rock
(iv) formation of extrusive rocks and intrusive rocks is:
- Extrusive rock are formed when molten magma cools down deep down inside the earth’s surface.
- Intrusive rocks are formed when molten magma cools down inside the earth’s crust.
(v) The change of one type of rock into another type under certain conditions in a cyclic manner is called a rock cycle.
(vi) Following are some uses of rocks:
- They are used as fuels.
- They are used in industries.
- They are used in medicines.
- They are used in fertilizers.
- They are used in making roads, houses, building etc.
(vii) The types of rocks formed when igneous and sedimentary rocks undergo heat and pressure are known as metamorphic rocks.
(i) (a) igneous
(ii) (b) core
(iii) (b) mineral
(iv) (a) sedimentary rocks
(v) (a) crust
(i) Core (e) innermost layer
(ii) minerals (d) has definite chemical composition
(iii) rocks (b) Used for roads and buildings
(iv) clay (f) change into slate
(v) sial (c) made of silicon and alumina
(i) We cannot go to the centre of the earth because the temperature as well as pressure is extremely high there. Not only human being but also rocks and metals got melted at this condition.
(ii) Rocks breakdown into smaller fragments under several conditions. These layers of sediments are made when loose sediments are compressed and hardened. These layers of sediments thus form sediments thus forms the sedimentary rocks.
(iii) Ingenious and sedimentary rocks change their size and shape under great pressure and temperature conditions to form metaphoric rocks. The same thing happens with limestone under the effect of heat and pressure change into marble, is an example of metamorphic rock.
Minerals of most commonly used objects:
1. Karhai Iron
2. Ornaments Gold, silver
3. Pan/tawa Iron
4. Bell Copper, zinc, iron
5. Hammer Iron
6. Lamp Copper, zinc
(ii) Spoon, Keys, Pen, Poles, Pipes, Ships, Planes, etc. are so many objects which are made up of minerals.
