common elements

[Sonyme]

What is the second most common element on earth?

[gen2]

Please refine your question.

A) By saying ON earth, do you mean
(i) 'On and above the earth's surface?
(ii) IN the earth's crust?
(iii) Within the earth as a whole?

B) By 'Most Common', do you mean:
(i) By mass?
(ii) By volume?
(iii) By number of atoms?

[moonshadow]

Oxygen

[Sonyme]

It is a question in a quiz and reads exactly as written in the question I posted . Google has produced silicon on one search and helium on another

[Teddio]

Second commonest element in the Earth's crust will be Silicon. Most of the crust is made of silicate rock (eg. SiO2 and KAlSi3O8) and the mantle is made largely of peridotite.

[elloras]

Hydrogen is the most abundant element in the known Universe; helium is second. However, after this, the rank of abundance does not continue to correspond to the atomic number; oxygen has abundance rank 3, but atomic number 8.