In terms of abundance of metals in the earth crust, which metal is the second most abundant after aluminium by mass?

Introduction / Context:
The composition of the earth crust is a very important topic in physical geography and general science. Examinations often ask about the relative abundance of elements and metals to test basic scientific awareness. In this question, you are asked to identify the second most abundant metal in the earth crust by mass, given that aluminium is the most abundant metal component of the crust.

Given Data / Assumptions:

• The focus is only on metals, not on all elements such as oxygen or silicon.
• Aluminium is considered the most abundant metal in the earth crust.
• We need to choose the second most abundant metal from iron, aluminium, copper, and zinc.

Concept / Approach:
Geochemical studies show that the earth crust consists mainly of oxygen and silicon, followed by aluminium and iron. Oxygen and silicon are non metallic elements. When we restrict attention only to metals, aluminium occupies the first position and iron follows as the second most abundant metal. Copper and zinc are important industrial metals but occur in much smaller concentrations compared to iron and aluminium. Remembering this simple order helps to answer quickly: aluminium first, iron second.

Step-by-Step Solution:
Step 1: Recall that non metals like oxygen and silicon form the largest share of the earth crust, but the question is about metals only.Step 2: Note that aluminium is the most abundant metal in the crust.Step 3: Remember that iron is very common in rocks and minerals, forming oxides and other compounds.Step 4: Recognise that copper and zinc occur in smaller, more localised ore deposits.Step 5: Conclude that iron is the second most abundant metal in the earth crust after aluminium.

Verification / Alternative check:
Standard data from school level geography and chemistry texts confirms that the approximate mass percentage in the crust is about: oxygen around forty six percent, silicon around twenty eight percent, aluminium around eight percent, and iron around five percent. Since only aluminium and iron are metals among these main constituents, aluminium is the most abundant metal and iron is next. This confirms that iron is correctly identified as the second most abundant metal.

Why Other Options Are Wrong:
Aluminium: This is the most abundant metal, not the second most abundant, so it does not match the requirement in the question.Copper: Copper is used widely in electrical and construction work but is geochemically much less abundant than iron and aluminium.Zinc: Zinc deposits are also relatively limited and never approach the widespread abundance of iron minerals.

Common Pitfalls:
Students sometimes mix up the order of abundance or confuse metals with general elements. Another mistake is to think of copper because of its commercial value and visibility in daily life, even though it is less abundant. Always distinguish between abundance in the crust and economic importance. The safe memory aid is that aluminium and iron dominate metallic components of the crust in that order.

Final Answer:
The second most abundant metal in the earth crust, after aluminium, is iron.