Earth's structure

Question 1

State the rate of increase in temperature as we go below the surface of the earth.

Answer 1

The rate of increase in temperature is 1 degree celcius every 32 m

Question 2

What is the depth of the source of lava eruption?

Answer 2

The depth is at 48km. The temperature at 48km is 1200 degree Celcius and at that temperature the layer of rock is molten.

Question 3

State the temperature at

i) 48 km
ii) inner core
iii) outer core
iv) 400 km

Answer 3

i) 1200 C
ii) 4300 C
iii) 2500 C
iv) 1500 C

Question 4

State the 3 factors that help us in understanding the composition and the structure of the earth beneath the surface.

Answer 4

1. Temperature
2. Pressure
3. Density

Question 5

i) one atmospheric unit equals _____ pounds per sq inch
ii) At 2500 km the pressure of the atmosphere is ___atm
iii) at 5100 km or at the core of the earth the pressure is ___atm

Answer 5

i) 14.7
ii) one million atm
iii) 3.5 million atm

Question 6

I) average density of earth \_\_\_\_
II) Density of Sial \_\_\_\_
III) density of Sima\_\_\_\_
What can you infer from the densities of Sial and Sima?
IV) Density of the core\_\_\_.

Answer 6

I) 5.5
II) 2.7
III) 2.95

Question 7

What is Lithosphere?

Answer 7

The word has been derived for the greek word “Lethos” meaning rock. The crust of the earth consisting of Sial and Sima, on the surface of which the life on Earth is sustained is known as the lithosphere.

Question 8

What is the earth’s crust?

Answer 8

The Earth’s crust is the outermost layer of the earth that sustains the life on earth. It is made up of two layers called Sial and Sima. The Earth’s crust is also known as lithosphere.

Question 9

What is Sial and Sima? What else can they be called as?

Answer 9

Sial is the upper layer of the earth’s crust which mainly consists of the continental parts of the earth. It has a density and composition similar to granite and is rich in silicon and aluminum. It can also be called as the granite layer. Sima is the lower layer of the earth’s crust under the ocean floor. It has density and composition similar to that of basalt. It is also known as the basaltic layer.

Question 10

Where is the crust thickest and where is it the thinnest?

Answer 10

The crust is the thickest below the mountains and thinnest under the ocean.

Question 11

What is the mantle and its layers? What is its depth and physical state?

Answer 11

The mantle is the second layer of the earth’s structure and is divided into upper mantle (Asthenosphere) and lower mantle (Mesosphere). The asthenosphere is in a molten state but the mesosphere is solidified due to the high pressure.

Question 12

What is the Mohorovic discontinuity and what is the Gutenberg discontinuity?

Answer 12

The zone of contact between the crust and the mantle is known as the Mohorovic discontinuity and the zone of contact between the mantle and the core is known as the Gutenberg discontinuity.

Question 13

Asthenosphere consists of ___, ____, ___,

Mesosphere consists of ____, ___

Answer 13

i) Iron silicates, Magnesium, Sulphides

ii) Iron and Nickel

Question 14

What is the core and what is its other name?

Answer 14

The core is the inner most part of the structure of the earth which starts from the Gutenberg discontinuity. It is located at a depth 5100km. The outer core at a temperature of 2700 c is in a molten state but the inner core at a temperature of 4300 C is solidified. The core is also known as Barosphere.

Question 15

How is Sial different from Sima?

Answer 15

Sial is less dense than Sima
Sial is discontinuous but Sima is continuous
Sial is rich in silicon and aluminium whereas Sima is rich in silicon and Magnesium.
Sial makes up the continental parts whereas Sima is below the ocean floor on which the Sial floats/

Question 16

What does Nife mean?

Answer 16

The core is made up of solidified Nickel and iron collectively known as Nife. The temperature of the molten outer core is 2700 c and the solidified inner core is 4300 C.