Which one of the following is present in the largest amount in terms of per cent by mass in the earth’s crust ?

Oxygen is the most abundant element in the Earth’s crust by mass. Standard crustal composition data show oxygen constitutes roughly 46.6% of the crust while silicon is the second most abundant at about 27.7%; calcium accounts for only about 3.6% [1]. Carbon is present in only trace amounts in the crust (approximately 0.02% in mineral forms such as carbonates, coal, and petroleum) and is therefore negligible compared with oxygen, silicon, and calcium [2]. Given these percentages, oxygen clearly occurs in the largest proportion by mass in the Earth’s crust, making option 2 the correct choice.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > The Crust > p. 53
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > p. 58