Question

What is the most abundant element on earth?
A. Hydrogen
B. Nitrogen
C. Oxygen
D. Silicon

Answer 1

Hint: Abundance of a chemical element is the percentage or measure of the occurrence of the chemical elements relative to all the other elements in a given environment. It is measured three ways- by the mass-fraction (the same as weight fraction), by the mole-fraction (fraction of atoms by numerical count or sometimes fraction of molecules in gases) or by the volume fraction.

Complete step by step answer:
Now we will discuss the given options one by one.
The first option is hydrogen. The electronic configuration of hydrogen is $1s^2$. In the combined form it is present about 15 $\mathrm{\%}$ on the earth’s crust.
The second option is Nitrogen. Nitrogen is the element of Group 15 with atomic number 7. Its electronic configuration is $1s^{2}2s^{2}2p^3$. A little amount of traces (0.002 $\mathrm{\%}$) of nitrogen is found in the earth’s crust.
The third option is oxygen. Oxygen is the chemical element of group 16 with atomic number 8. The electronic configuration of nitrogen is $1s^{2}2s^{2}2p^4$. It is the most abundant element on earth and it constitutes about 46.6 $\mathrm{\%}$ of the earth’s crust. It is found in the native as well as in the combined state.
The fourth option is Silicon. Silicon is a chemical element of group 14 with atomic number 14. The electronic configuration of Silicon is$1s^{2}2s^{2}2p^{6}3s^{2}3p^2$. It is the second most abundant element which constitutes about 27.7 $\mathrm{\%}$ of the earth’s crust.

So, the correct answer is Option C.

Note: More than 90 $\mathrm{\%}$ on the earth’s crust is composed of silicate minerals. Most abundant silicates are feldspars and alkali feldspar. Other common silicate minerals are quartz, pyroxenes, amphiboles, micas and clay minerals. The rest of the silicate family comprises 3 $\mathrm{\%}$ of the crust. Only 8 $\mathrm{\%}$ of the crust is composed of non-silicates. All silicates have a significantly high amount of oxygen.