UPSC Prelims 2009 Q35: Geography – Physical Geography & Geomorphology
In the structure of planet Earth, below the mantle, the core is mainly made up
of which one of the following ?
- (a) Aluminium
- (b) Chromium
- (c) Iron
- (d) Silicon
Answer: (c) Iron
Explanation
What Earth's core is mainly made of
Below the mantle, Earth's deep interior consists primarily of a specific dense metal.
| Option | Verdict | Reason |
|---|---|---|
| (a) Aluminium | Incorrect | Not the dominant core material |
| (b) Chromium | Incorrect | Present in trace amounts, but not the dominant core material |
| (c) Iron | Correct | Earth's core (both outer liquid and inner solid) is composed mainly of iron (along with some nickel) |
| (d) Silicon | Incorrect | Silicon is more associated with the crust and mantle, not the core |
Earth's internal structure:
| Layer | Composition |
|---|---|
| Crust | Silicate rocks |
| Mantle | Silicate minerals, denser than crust |
| Core | Mainly iron (with nickel) |
Answer: (c) Iron.
Why each option is right or wrong
- (a) Incorrect. Aluminium is not the dominant core material.
- (b) Incorrect. Chromium is present only in trace amounts, not dominant.
- (c) CORRECT. Earth's core is mainly composed of iron (with some nickel).
- (d) Incorrect. Silicon is associated with the crust and mantle, not the core.
Key point
Earth's core, below the mantle, is composed mainly of IRON (along with some nickel) — not aluminium, chromium, or silicon, which are associated with other layers.
Remember
Earth's core, below the mantle, is mainly composed of iron.
Common mistakes
- Confusing core composition (iron/nickel) with crust/mantle composition (silicate minerals).
- Not knowing iron's specific dominant role in both the outer liquid and inner solid core.
- Mixing up different elements' roles across Earth's layered structure.
Exam tip
Earth's core = mainly iron (plus nickel). Crust and mantle = silicate-based. A fundamental Earth-structure fact.
Sources
- NCERT Class XI Geography — Fundamentals of Physical Geography — Interior of the Earth
- Encyclopaedia Britannica — Earth