1.
The oceanic crust mainly consists of silica and magnesium; it is therefore called Sima.
2.
Option A
3.
The molten magma cools down and solidifies into igneous rocks.
4.
Concentric
5.
Coal, natural gas and petroleum are examples of fuel.
6.
To reach the centre of the earth one will have to dig a hole 6000 km deep on the ocean floor.
7.
Mantle
8.
Option A
9.
Option A
10.
Primary rocks
11.
Option B
12.
Clay changes into slate and limestone into marble.
13.
Option A
14.
When the igneous and sedimentary rocks are subjected to heat and pressure they change into metamorphic rocks.
15.
Option B
16.
Minerals
17.
Cyclic manner
18.
Igneous rock
19.
Wind
20.
There are two types of igneous rocks are intrusive rocks and extrusive rocks.
