Environmental Chemistry

CO2, O3, H2O, CFCs are green house gases. Here only O2 is not greenhouse gas.

Calcination Releases $\to$ CO2 $\to$ Global warming Roasting Releases $\to$ SO2 $\to$ Acid Rain

Thermal power plants lead to acid rain.

Option A Both Statement I and Statement II are true.

Explanation : The pH of pure water is 7, which is considered neutral.

However, rainwater is naturally slightly acidic due to the presence of dissolved carbon dioxide, which reacts with the water to form carbonic acid.

The pH of "normal" rainwater is around 5.6 because of this natural process.

Acid rain is a term that refers to any form of precipitation with acidic components, such as sulfuric or nitric acid, that fall to the ground from the atmosphere in wet or dry forms.

This can include rain, snow, fog, hail or even dust that is acidic.

The increased acidity in rain is caused by high amounts of pollutant components such as sulfur and nitrogen compounds which react in the atmosphere with water, oxygen, and other chemicals to form sulfuric and nitric acid.

These then fall to the ground as acid rain.

The generally accepted definition of "acid rain" refers to rainfall with a pH of less than 5.6, which is more acidic than normal rainwater.

Photochemical smog is a type of air pollution that results from the interaction between sunlight and pollutants such as nitrogen oxides and volatile organic compounds (VOCs).

This type of smog is common in urban and industrial areas where there is a high concentration of these pollutants.

The conditions favorable for the formation of photochemical smog include strong sunlight, stagnant air, and the presence of pollutants such as those emitted by vehicles and industrial processes.

Given the options: Option A : Industrial areas - These typically have a high concentration of pollutants like nitrogen oxides and VOCs that can interact with sunlight to form photochemical smog.

Option B : Himalayan villages in winter - Likely to have less sunlight and fewer pollutants.

Option C : The places with healthy vegetation - Vegetation can actually help to reduce smog by absorbing pollutants.

Option D : Marshy lands - Unlikely to have the concentration of pollutants necessary for photochemical smog formation.

The correct answer is : Option A : Industrial areas.

The lowest region of atmosphere in which human beings live is troposphere.

It extends up to a height of 10 km from sea level.

Clouds are also formed in this layer

Statement I : If BOD is 4 ppm and dissolved oxygen is 8 ppm, then it is a good quality water.

Statement II : If the concentration of zinc and nitrate salts are 5 ppm each, then it can be a good quality water.

The Biochemical Oxygen Demand (BOD) measures the quantity of oxygen used by microorganisms in the oxidation of organic matter.

Lower values of BOD indicate better water quality.

A BOD value of less than 5 ppm indicates good quality water.

Therefore, in Statement I, the BOD value of 4 ppm indicates good water quality.

Dissolved oxygen (DO) refers to the level of free, non-compound oxygen present in water.

DO levels above 5-6 ppm are generally good for aquatic life.

In Statement I, the DO level of 8 ppm suggests the water is of good quality.

The concentration of zinc in clean water should not exceed 5 ppm and the concentration of nitrates should not exceed 50 ppm.

In Statement II, both zinc and nitrate concentrations are given as 5 ppm, which are within their respective permissible limits, therefore suggesting the water can be of good quality.

Hence, based on this analysis : Option C : Both the statements I and II are correct.

Option A (manufacturing of cement) is a significant contributor to global greenhouse gas emissions, as the production of cement releases large amounts of carbon dioxide (CO2).

Option B (electricity generation in thermal power plants) is also a major contributor, as burning fossil fuels such as coal, natural gas, and oil to generate electricity releases large amounts of CO2 and other greenhouse gases into the atmosphere.

Option C (steel manufacturing) also has a significant impact, as the production of steel requires high temperatures and the use of large amounts of energy, which can come from the burning of fossil fuels.

Option D (Industrial production of urea) has a lower impact compared to the other options, as it is a less energy-intensive process and does not directly release greenhouse gases into the atmosphere.

However, the production of urea does rely on the use of natural gas as a feedstock, which does result in the release of some greenhouse gases.

Reducing smog as is acts as reducing agent, the reducing character is due to presence of sulphur dioxide and carbon particles.

Taj mahal is slowely disfigured and discoloured due to acid rain.

The primary acid component of acid rain is sulfuric acid(H2SO4) which reacts with Marble(CaCO3) and gives aqueous ion.

This aqueous ions get washed away in the water flow and marble get disfigured and discoloured.

CaCO3(s) + H2SO4 $\to$ Ca2+(aq) + SO42-(aq) + H2O + CO2