Problem 63 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Among the following, the correct statement is (a) Phosphates have no biological significance in humans (b) Between nitrates and phosphates, phosphates are less abundant in earth's crust (c) Between nitrates and phosphates, nitrates are less abundant in earth's crust (d) Oxidation of nitrates is possible in soil

Step-by-Step Solution

Answer

The correct statement is (c).

Step 1: Analyze Statement (a)

Statement (a) claims that phosphates have no biological significance in humans. However, phosphates are critical in numerous biological processes, including bone and teeth formation, as well as energy transfer through ATP. Therefore, statement (a) is incorrect.

Step 2: Analyze Statement (b)

Statement (b) suggests that phosphates are less abundant than nitrates in the Earth's crust. In reality, phosphates (primarily found as mineral apatite) are more abundant than nitrates in the Earth's crust. Thus, statement (b) is incorrect.

Step 3: Analyze Statement (c)

Statement (c) asserts that nitrates are less abundant than phosphates in the Earth's crust. Since phosphates are indeed more abundant than nitrates in the crust, this statement is correct.

Step 4: Analyze Statement (d)

Statement (d) indicates that oxidation of nitrates is possible in soil. Nitrates are generally the end product of the oxidation process of nitrogen compounds; therefore, this statement is incorrect as nitrates themselves do not undergo further oxidation naturally in soil conditions.

Step 5: Determine the Correct Statement

Based on the analysis of each option, the correct statement is (c), as it accurately describes the relative abundance of nitrates and phosphates in the Earth's crust.

Key Concepts

Biological Significance of Phosphates

Phosphates play a crucial role in living organisms, including humans. They are essential for many biological processes:

• Bone and Teeth Formation: Phosphates are key components of calcium phosphate, which makes up a substantial part of bone and teeth structure. This ensures strength and durability.
• Energy Transfer: Phosphates are integral to adenosine triphosphate (ATP), the energy currency of the cell, facilitating energy transfers necessary for various cellular functions.
• Cell Membrane Structure: Phospholipids, which contain phosphates, are essential components of cell membranes, helping maintain cell structure and function.
• Genetic Material: DNA and RNA, our genetic blueprints, have sugar-phosphate backbones, highlighting phosphates' role in genetic information storage and transfer.

Without phosphates, these critical biological functions would be disrupted, underscoring their significance in human biology.

Phosphate Abundance

Phosphates are quite abundant in the Earth's crust, primarily found in the form of the mineral apatite. This prevalence is significant for several reasons:

• Geological Distribution: Phosphates are distributed widely in various rock forms, making them accessible for extraction and use in agriculture and industry.
• Agricultural Use: Phosphates are vital components of agricultural fertilizers. They contribute to plant growth by improving root development and increasing crop yields.
• Ecosystem Support: Natural weathering of phosphate rocks releases phosphates into the soil, which supports plant growth and thus maintains ecosystem health.

Given their integral role in both natural and human-made systems, phosphates are anything but scarce in the Earth's crust.

Nitrate Abundance

Nitrates, compared to phosphates, are less abundant in the Earth's crust. However, they are still vital for several reasons:

• Plant Nutrition: Nitrates are a major source of nitrogen for plants, crucial for synthesizing amino acids and proteins.
• Soil Fertility: Nitrogen in soil, often in nitrate form, enhances soil productivity by promoting healthy plant growth.
• Agricultural Fertilizers: Although not as common as phosphates, nitrates are key components in fertilizers, supplementing nitrogen to improve crop production.

Despite their lesser abundance, nitrates play critical roles in agricultural productivity. Still, they must be managed carefully due to their high solubility and potential for leaching into waterways.

Soil Oxidation Process

The soil oxidation process involves the transformation of nitrogen compounds, but not nitrates themselves. Here's why:

• Oxidation of Nitrogenous Compounds: Nitrogen in the soil undergoes a process called nitrification, where ammonia is oxidized to nitrites and then to nitrates.
• Nitrate's Role: Nitrates are the final products of this oxidation process, meaning they do not get oxidized further under natural soil conditions.
• Environmental Impact: The stability of nitrates in the soil makes them critical for plant uptake, but it also poses a risk of leaching, which can lead to water contamination.

Understanding the soil oxidation process highlights the importance of nitrogen cycling in the environment and the need for careful management of nitrate levels in soils to prevent environmental issues.