Explanation

1. Oxygen: The most abundant element in the Earth's crust, making up about 47% of the Earth's mass.
2. Silicon: The second most abundant element in the Earth's crust, making up about 27.7% of the crust 
3. Aluminum: The third most abundant element in the Earth's crust, making up around 8.1%.

Explanation

The least polluted gas chlorine.

The most polluted gas is carbon monoxide.

Explanation

A polyp is a projecting growth of tissue from a surface in the body, usually a mucous membrane.

Polyps can develop in the: colon and rectum (ear canal).

Explanation

The sun is containing 99.86 % mass of the solar system

Explanation

The Nutrient Cycle is the most natural event in the context of nutrient cycling.

It refers to the continuous process by which nutrients are exchanged between the environment, plants, and animals.

This process includes various events such as primary production, decomposition, and nutrient uptake.

Explanation

Biogas produced as a result of anaerobic decay of organic matter consists primarily of methane (CH4) and carbon dioxide (CO2).

Biogas can also contain small amounts of other gases, such as:

• Water vapor
• Hydrogen sulfide (H2S
• Siloxanes

Explanation

Pathology is the branch of science that focuses on the causes, effects, and nature of diseases in organisms.

It studies both the structure and function of diseased tissues and organs.

Explanation

Isotopes: scientific name of the atoms of the same element with different mass numbers.

Explanation

In Karst topography, both gypsum and dolomite are soluble.

They can form karst landscapes through dissolution.

This process is similar to limestone, though it occurs at varying rates.

Explanation

Magma that is low in silica and high in iron and magnesium is mafic magma.

Mafic magma is also known as basaltic magma

Silica content: Mafic magma has a silica content of roughly 50%. 

Mafic magma contains dark-colored minerals, such as olivine and pyroxene,