Understanding Earth's Crust Composition

The Earth's crust is the outermost solid shell of our planet. It is composed of various elements, but some are much more common than others. This question asks us to match four specific common elements with their approximate percentage by weight in the Earth's crust.

Elemental Abundance in Earth's Crust

Scientists have studied the composition of the Earth's crust extensively. The most abundant elements are primarily Oxygen and Silicon, which form the bulk of silicate minerals. Other relatively abundant elements include Aluminum and Iron.

Here are the approximate percentages by weight of the elements listed in Column A:

• Oxygen (O): Approximately 46.6%
• Silicon (Si): Approximately 27.7%
• Aluminum (Al): Approximately 8.1%
• Iron (Fe): Approximately 5.0%

Analyzing the Matching Columns

We are given two columns to match:

Performing the Element Percentage Matching

Let's match each element from Column A with its corresponding percentage from Column B based on the known abundances:

• i. Si (Silicon): We know Silicon makes up about 27.7% of the Earth's crust. Looking at Column B, option b is 27.7%. So, i matches b.
• ii. O (Oxygen): Oxygen is the most abundant element, making up about 46.6%. Looking at Column B, option a is 46.6%. So, ii matches a.
• iii. Al (Aluminum): Aluminum makes up about 8.1% of the Earth's crust. Looking at Column B, option d is 8.13%, which is very close to 8.1%. So, iii matches d.
• iv. Fe (Iron): Iron makes up about 5.0% of the Earth's crust. Looking at Column B, option c is 5.0%. So, iv matches c.

Summary of the Matching

Putting the matches together, we get the following pairings:

• i - b
• ii - a
• iii - d
• iv - c

This set of pairings corresponds to one of the options provided in the question.

Revision Table: Common Elements in Earth's Crust and Their Abundance

Here is a table summarizing the approximate percentages of the most abundant elements in the Earth's crust for quick review:

Additional Information on Earth's Crust Composition

The composition of the Earth's crust is crucial for understanding geological processes, resource availability, and environmental cycles. These percentages are average values for the continental crust and oceanic crust combined, or sometimes specifically for the continental crust which is more accessible for sampling.

The elements exist in the crust primarily in the form of minerals. For example, Silicon and Oxygen combine with metals like Aluminum, Iron, Calcium, Sodium, Potassium, and Magnesium to form silicate minerals, which are the most common type of mineral in the crust.

While these eight elements make up the vast majority (over 98%) of the Earth's crust, many other elements are present in much smaller trace amounts.