The Earth Archives

What is the approximate percentage of carbon in the Earth’s crust ?

0.045%

0.025%

0.015%

0.005%

This question was previously asked in

UPSC CDS-2 – 2021

The Earth’s crust is primarily composed of silicate minerals. While carbon is abundant on Earth as a whole (present in the atmosphere, oceans, biosphere, and mantle), its percentage in the *crust* specifically (excluding the organic component and sedimentary rocks like carbonates which are often considered part of the crust but distinct in geological abundance statistics) is relatively low compared to elements like oxygen, silicon, aluminium, iron, etc. Carbon exists in the crust mainly in carbonate rocks (limestone, dolomite), coal, petroleum, and organic matter. Estimates for the abundance of carbon in the Earth’s crust typically fall in the range of 0.03% to 0.05% by weight. Looking at the options provided, 0.045% falls within this commonly cited range, making it the most likely correct answer.

– The Earth’s crust is dominated by silicates.
– Carbon in the crust is mainly found in carbonates and organic matter.
– Its percentage by weight is relatively low compared to the major rock-forming elements.

The lithosphere (crust and upper mantle) contains significantly more carbon than the atmosphere, oceans, and biosphere combined, primarily stored in carbonate rocks formed over geological time. The total amount of carbon on Earth is vast, but its distribution across different reservoirs is uneven.

Which of the following statements is / are correct ?

1. The earth is nearest to the Sun at Perihelion, which generally occurs on January 3
2. The earth is farthest away from the Sun at Perihelion, which generally occurs on July 4
3. The earth is farthest away from the Sun at Aphelion, which generally occurs on July 4
4. The earth is nearest to the Sun at Aphelion, which generally occurs on January 3

Select the correct answer using the code given below :

1 only

2 and 4

1 and 3

1 and 2

This question was previously asked in

UPSC CDS-1 – 2016

Download PDF Attempt Online

Statements 1 and 3 are correct.

– Perihelion is the point in the Earth’s orbit where it is nearest to the Sun. This generally occurs around January 3rd each year.
– Aphelion is the point in the Earth’s orbit where it is farthest from the Sun. This generally occurs around July 4th each year.
– The slight eccentricity of the Earth’s orbit causes this variation in distance, although it is not the primary reason for the seasons (axial tilt is).

Statement 2 is incorrect because Perihelion is when the Earth is nearest, not farthest. Statement 4 is incorrect because Aphelion is when the Earth is farthest, not nearest.

11. What is the approximate percentage of carbon in the Earth’s crust ?

12. Which of the following statements is / are correct ? 1. The earth is