Match the location with its two most common elements.
Earth’s crust
Universe
The entire Earth
- silicon and oxygen
- hydrogen and helium
- oxygen and iron
The correct answer and explanation is :
Here is the correct matching of each location with its two most common elements:
- Earth’s crust: silicon and oxygen
- Universe: hydrogen and helium
- The entire Earth: oxygen and iron
Explanation (300+ words):
Understanding the composition of different parts of our planet and the universe helps us grasp fundamental scientific principles in geology, chemistry, and astronomy. Each location—Earth’s crust, the entire Earth, and the universe—has a distinct chemical makeup based on the processes that shaped them.
1. Earth’s Crust: Silicon and Oxygen
The Earth’s crust, the outermost solid shell, is composed primarily of silicon (Si) and oxygen (O). These two elements combine to form silicate minerals, which make up over 90% of the Earth’s crust. The most abundant of these minerals include quartz (SiO₂) and feldspars. Oxygen makes up about 46% and silicon about 28% by weight of the crust. Their abundance is due to their chemical stability and ability to form compounds like silicates, which are common in igneous, metamorphic, and sedimentary rocks.
2. Universe: Hydrogen and Helium
The universe is dominated by hydrogen (H) and helium (He), which are the lightest and simplest elements. Hydrogen makes up roughly 74% and helium about 24% of the universe by mass. These elements were formed in the first few minutes after the Big Bang through a process called Big Bang nucleosynthesis. Stars primarily burn hydrogen into helium through nuclear fusion. Heavier elements exist but in much smaller quantities, typically formed in the cores of stars and during supernova explosions.
3. Entire Earth: Oxygen and Iron
When considering the entire Earth, including the mantle and core, oxygen (O) and iron (Fe) are the most common elements. Oxygen remains the most abundant due to its presence in silicate minerals throughout the mantle. Iron, on the other hand, dominates the Earth’s core, making up about 35% of Earth’s total mass. The core is mostly iron-nickel alloy, contributing significantly to the planet’s magnetic field.