Earth's Structure

A is false but R is true.

Explanation — Sial floats on Sima, as Sial is less dense than Sima.

Both A and R are true and R is the correct explanation of A.

Explanation — The Gutenburg discontinuity is situated between the Mantle and the core. This is the area where some earthquake waves are absorbed or change speed, hence there is sudden change in the velocity of these waves.

Earth's outer shell of crystalline surface rock, ranging from 6 to 48 km in thickness from oceanic crust to mountain ranges is known as lithosphere.

The two layers of lithosphere are:

1. Sial
2. Sima

It is the layer of silicate rock between the crust and the outer core. The depth of Mantle varies between 35 to 2900 km. It consists of dense and rigid rocks containing magnesium and iron. The Mantle is divided into two parts:

1. the Upper Mantle or Asthenosphere
2. the Lower Mantle or the Mesosphere

The mantle layer lies between the crust and the core of earth. Its upper boundary is marked by Mohorovicic Discontinuity and its lower boundary is marked by the Gutenburg Discontinuity.

The central part of earth that probably consists of dense nickel and iron alloy (Nife) is known as core. It is also known as Barysphere. It's temperature is estimated to be about 2700°C.

SIAL layer consists of Silica and Aluminium.

The properties of the core of the Earth are:

1. It consists of Nickel and Iron with a temperature estimated to be 2700°C.
2. The inner core also consists of nickel and iron and is forced into a solid state by increased pressure.

The earth's crust consists of two layers - SIAL and SIMA.

The material of the upper or continental part of the earth's crust, characterized by relatively low density is called the SIAL layer.The SIAL layer has predominance of Silica and Aluminium. It is also known as granite layer which floats on SIMA.

The lowest layer of the earth's outer crust that underlies the SIAL is SIMA layer. It consists of Silica and Magnesium and it is also known as basaltic layer.

'Nife' is the name given to the core of the Earth as it is rich in Nickel and Ferrous(iron) alloy.

High pressure in the interior of the earth exercises a powerful influence on the temperature and physical state of the earth. The temperature of the earth's interior goes on increasing at the rate of 1°c for every 32 metres. Thus, the temperature increase as we go down(underground).

The two most important and abundant chemical elements present in the Earth's crust are Silica and Oxygen.

The contact zone of the Crust and Mantle is called Mohorovicic Discontinuity.

The Mantle layer is composed of magnesium and iron silicates, along with substantial quantities of sulphides in the upper mantle and nickel and iron in the lower mantle.

Temperature increases at the rate of 1°C for every 32 metres of descent.

Crust

Silica & Magnesium

Core & Mantle

Mantle

Partially Molten

2900

Core

high pressure

Granite, Si, Al.

5.5

Mohorovicic

Earth's outer shell of crystalline surface rock, ranging from 4 to 48 km in thickness from oceanic crust to mountain ranges is called Crust.

The layer of Iron and Magnesium silicate rock and nickel and iron alloy between the crust and the outer core with depth varying from 35 to 2900 km is called Mantle.

The central part of earth that probably consists of dense nickel and iron alloy is known as core.

The core of earth consists of nickel and iron alloy and is known as Nife.

Below diagram shows the composition and structure of the Earth:

The core of the Earth is also called 'Nife' as it is rich in Nickel and Ferrous(iron) alloy.

The inner core of the earth is forced into a solid state by increased pressure, that is three million tonnes greater at the center of the earth than at the surface.

The Earth’s core, especially the outer core, is made up of molten iron and nickel. Due to the rotation of the Earth, these liquid metals move and generate electric currents. This movement of electrically charged fluid produces a magnetic field around the Earth.

This phenomenon is called the dynamo effect, and it is the reason why the Earth behaves like a giant magnet, with a North and South Magnetic Pole.

The temperature inside the Earth increases with depth, about 1°C for every 32 meters. In the mantle region, temperatures can reach around 2200°C. At such high temperatures, rocks melt and exist in a hot, molten state called magma. During volcanic eruptions, this extremely hot magma rises and escapes to the surface, which is why the material that comes out is always hot.

The Earth's magnetic field is generated by its core, which is composed mainly of iron and nickel. The movement of molten iron in the outer core creates electric currents, which in turn produce the magnetic field. This magnetic field acts as a shield, protecting our atmosphere from harmful solar winds