Question

The thinnest layer of the Earth is _________
a. Crust
b. Mantle
c. Inner core
d. Outer core

Answer 1

Hint: The layers of Earth can be classified into two types- based on chemical composition and the basis of physical properties. The crust is the outermost layer with room for geological activities.

Complete answer:The crust is not only the outermost layer but it is also the thinnest layer. The average thickness of the crust can be said to be around 40 kilometres. It is also divided into fifteen major tectonic plates. These plates have a rigid centre but there is room for geological activities at the boundaries such as volcanism. The mantle is hot and dense. Its temperature ranges from 932 to 1,652 degrees Fahrenheit. It has a movement similar to a semi-solid rock. The mantle is 2,900 km in thickness and comprises silicate minerals that are similar to the ones found inside the crust. However, there is more magnesium and iron and fewer amounts of silicon and aluminium. The outer core’s temperature ranges between 7,200 and 9,000 degrees Fahrenheit. It is estimated to be 2,300 km in thickness. It is composed mostly of iron and nickel, that too in their liquid form. It is the movement of the liquid present within the outer core that is responsible for generating Earth’s magnetic field. The hottest part is the inner core which has temperatures between 9,000 and 13,000 degrees Fahrenheit. This layer is 1,200 km thick and mostly composed of iron.

Therefore, the option “a” is the correct answer.

Note: Based on the physical properties of the composition of Earth’s layers there are five. These are the exosphere, troposphere, stratosphere, mesosphere, and thermosphere. The lowest is the troposphere.