The earth is made up of several concentric layers. The correct order of the layers from the centre to the surface is

1. Crust — Mantle — Core
2. Core — Mantle — Crust
3. Mantle — Crust — Core
4. Mantle — Core — Crust.

Name the two broad divisions the earth crust is divided depending on chemical composition.

1. Lithosphere, hydrosphere
2. SIAL, SIMA
3. Core, Mantle
4. Crust, Asthenosphere

This is the densest part of the earth believed to be composed of iron and nickel which is responsible for earth's magnetism. Identify it.

1. Mantle
2. Core
3. Crust
4. None of the above

Assertion (A): Sial appears to float above Sima.

Reason (R): Sial has lower density than Sima.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.