Question 1

What is the uppermost layer over the earth's surface called?

Accepted Answer

The uppermost layer over the earth's surface is called the crust. It is the thinnest of all the layers, about 35 km on the continental masses and only 5 km on the ocean floors.

Question 2

Which of the following is the main mineral component of the continental mass?

Accepted Answer

The main mineral components of the continental mass are silica and alumina. Therefore, it is called sial (si-silica and al-alumina).

Question 3

The oceanic crust mainly consists of which minerals?

Accepted Answer

The oceanic crust mainly consists of silica and magnesium; therefore, it is called sima (si-silica and ma-magnesium).

Question 4

What percentage of the earth's volume constitutes the crust?

Accepted Answer

The crust forms only 1 percent of the volume of the earth, 84 percent makes up the mantle and 15 percent makes up the core.

Question 5

What is the radius of the earth?

Accepted Answer

The radius of the earth is 6371 km, which is the distance from the surface to the innermost center of the earth.

Inside Our Earth — NCERT Class 7 Social Science Important Questions & Revision Notes