Which metal is the most abundant in the Earth crust by percentage of weight?

Introduction / Context:

This question tests basic geochemistry and general science knowledge. The Earth crust is composed of various elements and compounds, and some metals are more abundant than others. Knowing which metal dominates in terms of percentage composition is useful in understanding mineral resources and the distribution of ores in the crust.

Given Data / Assumptions:

• The question refers specifically to the Earth crust, not the entire Earth including core and mantle.
• We are comparing metals such as zinc, copper, aluminium, iron and calcium.
• Abundance is measured by percentage of weight in the crust.
• Standard geochemical data show relative abundance of elements in the crust.

Concept / Approach:

Oxygen and silicon are the most abundant elements in the crust overall, forming silicate minerals. Among metals, aluminium is the most abundant, followed by iron, calcium, sodium, potassium and magnesium. Aluminium is present mainly in feldspars and clay minerals. Copper and zinc are far less abundant and mainly occur in limited ore deposits. The approach is to recall this order and identify the leading metal by crustal abundance.

Step-by-Step Solution:

Verification / Alternative check:

Reference tables of crustal composition show approximate weight percentages: oxygen around 46 percent, silicon about 28 percent, aluminium around 8 percent and iron around 5 percent. Copper and zinc are present at trace levels far below 1 percent. These numbers confirm that aluminium is indeed the most abundant metal in the crust by weight. Many school textbooks also explicitly state this fact in sections about minerals and ores.

Why Other Options Are Wrong:

Zinc is an important industrial metal but is geochemically rare compared with aluminium and iron. Copper is also relatively scarce, found mainly in sulphide and oxide ores and not as a major crustal component. Iron is abundant and forms many minerals, but its overall crustal proportion is still lower than that of aluminium. Calcium, while significant in limestone and some silicate minerals, is not as abundant as aluminium when considered purely as a metal element. Therefore, these alternatives do not match the highest abundance level.

Common Pitfalls:

Students sometimes select iron because it is familiar and heavily used in industry, forgetting that abundance in use is not always equal to abundance in the crust. Others may be misled by the fact that aluminium is not found free in nature and requires complex extraction, which might make it seem rare. The key is to remember that aluminium occurs in many different minerals, giving it a high overall crustal percentage despite the difficulty of extraction.

Final Answer:

The most abundant metal in the Earth crust by weight is Aluminium.