Problem 72 - A Complete Resource Book in Chemistry for JEE Main

Question

Which statements are correct here? (1) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) particulates have size of \(500-1000 \mathrm{~nm}\). (2) Soot particles have a diameter of about \(5 \mathrm{~nm}\). (3) Fly ash particles have diameter of \(5 \times 10^{5} \mathrm{~nm}\). (a) 1 and 2 (b) 2 and 3 (c) 1 and 3 (d) 1,2 and 3

Step-by-Step Solution

Answer

(a) 1 and 2

Step 1: Understand Particulate Sizes

First, we must understand the typical size ranges for the particles mentioned. \(\mathrm{H}_{2}\mathrm{SO}_{4}\) particulates generally range from several hundred nanometers to a few micrometers, which aligns with the given size (500-1000 nm). Soot particles are typically much smaller, usually in the range of a few nanometers to tens of nanometers. The given size (5 nm) is reasonable for soot. Fly ash particles are generally larger, often in the range of micrometers, so 500,000 nm (or 500 micrometers) appears too large for typical fly ash particles.

Step 2: Verify Each Statement

Now, verify each statement:1. \(\mathrm{H}_{2}\mathrm{SO}_{4}\) particulates at 500-1000 nm: Correct. This size range is typical for such particles.2. Soot particles at 5 nm: Correct. Soot particles are this small or slightly larger.3. Fly ash particles at 500,000 nm: Incorrect. This size is excessively large since typical fly ash particles are smaller, i.e., around micrometers.

Step 3: Determine Correct Statements

Based on verification:- Statement 1 is correct (\(\mathrm{H}_{2}\mathrm{SO}_{4}\) particulates size is accurate).- Statement 2 is correct (Soot particles size is reasonable).- Statement 3 is incorrect (Fly ash particles size is too large).Thus, the correct statements are 1 and 2.

Key Concepts

H2SO4 particles

Sulfuric acid particles, known chemically as \(\mathrm{H}_{2}\mathrm{SO}_{4}\), are tiny, reactive particles that can be found in industrial areas and in the atmosphere. They are typically formed during combustion processes when sulfur dioxide \(\mathrm{SO}_2\) combines with water vapor. These particles often range from a few hundred nanometers to several micrometers in size, due to their generation processes.

This makes the size range of 500-1000 nm, as mentioned in the exercise, accurate for \(\mathrm{H}_{2}\mathrm{SO}_{4}\) particles. Here's why these particles matter:

• Sulfuric acid particles can contribute to air pollution and health issues, such as respiratory problems.
• They can also play a role in acid rain formation, affecting ecosystems and infrastructure.
• Understanding their size is crucial for managing air quality and assessing environmental impacts.

Managing and monitoring these particles is important for both public health and environmental protection. Various industries have implemented technologies to reduce \(\mathrm{H}_{2}\mathrm{SO}_{4}\) emissions as part of their sustainability efforts.

Soot particles

Soot particles are tiny, carbon-based particles that result from incomplete combustion of fossil fuels and biomass. They are a common component of air pollution and are known for their extremely small size, often falling within a range of a few nanometers to tens of nanometers.

This makes the given size of 5 nm a reasonable estimate for soot particles. Soot has several important characteristics:

• Their small size allows them to remain suspended in the atmosphere for long periods, traveling great distances from their source.
• Soot contributes to atmospheric warming, as the dark particles absorb sunlight and re-emit it as heat.
• Inhaled soot particles can penetrate deep into the lungs, posing significant health risks and contributing to respiratory and cardiovascular diseases.

Regulating soot emissions is an integral part of improving air quality. Measures include adopting cleaner technology for engines and industries, and increasing the use of renewable energy sources.

Fly ash particles

Fly ash is a byproduct of coal combustion in power plants and is comprised of fine particles. These particles are captured from the exhaust gases before they are released into the atmosphere. They generally range from a few micrometers to several micrometers in size, quite larger than the other particles discussed here.

In the exercise, the mentioned size of 500,000 nm (or 500 micrometers) is too large for typical fly ash particles, as they are usually only a fraction of that size. Key considerations about fly ash particles include:

• They can be beneficially used in construction as a replacement for Portland cement in concrete, helping to improve material properties and sustainability.
• When not managed properly, fly ash can contribute to air pollution and land contamination.
• Proper disposal and utilization of fly ash are essential for minimizing environmental impact.

Efforts to manage fly ash involve innovative reuse processes and stringent environmental regulations to ensure they don't pose health or environmental risks.