Question

The middle layer of the earth’s interior is called
A. Mantle
B. Core
C. Crust
D. Magma

Answer 1

Hint:
The middle layer is semi-liquid and makes up 84% of Earth's volume.
It is further divided into 3 main zones, the lithosphere, asthenosphere, and mesosphere.

Complete answer:
Earth consists of four distinct layers. From shallowest to deepest, these are the crust, mantle, the inner core and the outer core.

Layers of Earth

1. Crust

What we walk on every day is the earth’s crust only. It is the outermost thin layer that surrounds the Earth and ranges in temperature from 500 to 1,000°C. It is divided into two types: continental and oceanic. Earth's crust is 5 to 70 km thick.

Continental crust is thicker (35 - 70 km) and makes up the land on Earth. It is less dense and mostly made up of the rock granite.

Oceanic crust is thinner (5 - 7 km) and makes up most of the ocean. It is denser and mostly made up of the rock basalt.

2. Mantle

The mantle lies just below the crust. It is semi-liquid and makes up 84% of Earth's volume. Earth's mantle is 2,900 km thick and is divided into 3 main zones, the lithosphere, asthenosphere, and mesosphere.

The lithosphere makes up both the lower part of the crust and upper part of the mantle. It consists of the 15 major tectonic plates on Earth and is about 100 Km thick.

The mantle turns much more fluid in the asthenosphere and flows, allowing the above lying tectonic plates to drift across Earth.

Mesosphere is the deepest part of the mantle where temperature and pressure can get extreme.

3. Outer Core
The outer core lies beneath the mantle. This liquid iron and nickel layer spins as the planet rotates and this relative movement is responsible for the Earth’s magnetic field. This magnetic field protects us from solar radiation.

The outer core is 2,200 km thick and its hottest part is actually hotter than the inner core; temperatures can reach 6,000° Celsius which is as hot as the surface of the sun.

4. Inner Core
The inner core is the deepest layer. It is also made up of iron and nickel but they are no longer liquid because of the extreme pressure. The temperature in the inner core is about 5505 °C. The inner core of the Earth is 1,230 to 1,530 km thick.

Therefore the correct answer is A

Note:
Earth's inner core is growing at a very slow rate i.e., by 1mm per year.
More of the outer core solidifies and becomes a part of the inner core, as the core cools down.

Eventually, the entire outer core will solidify and become a part of the inner core. But don't worry, that won't happen for many billions of years.