MCH-023 Solved Assignment January 2026 | ENVIRONMENTAL CHEMISTRY | IGNOU MSCCHEM

Q1. Explain the following in brief.

i)) Soil profile (100 words)
ii)) Topography (100 words)
iii)) Parent material (100 words)
iv)) Metamorphic rocks (100 words)
v)) Granular disintegration (100 words)

Key Points:

Soil profile is a vertical cross-section of soil showing distinct horizons (O, A, B, C, R) formed during soil development.
Topography describes land's physical features like elevation and slope, impacting soil erosion, water flow, and microclimate.
Parent material is the initial geological or organic base from which soil forms, dictating its fundamental properties.
Metamorphic rocks are transformed from pre-existing rocks by intense heat, pressure, and chemical alteration.

Answer: Here's an explanation of the requested environmental chemistry terms, drawing from the MCH-023 course context. **i) Soil profile** A soil profile is a vertical cross-section of the soil, extending from the surface down to the parent rock. It reveals distinct horizontal layers, called horizons, which differ in physical, chemical, and biological characteristics. These horizons, typically designated as O, A, B, C, and R, represent stages of soil development. The O horizon consists of organic matte...

Q1. How is the soil texture analysis done? Describe in brief.

Key Points:

Soil profile is a vertical cross-section of soil showing distinct horizons (O, A, B, C, R) formed during soil development.
Topography describes land's physical features like elevation and slope, impacting soil erosion, water flow, and microclimate.
Parent material is the initial geological or organic base from which soil forms, dictating its fundamental properties.
Metamorphic rocks are transformed from pre-existing rocks by intense heat, pressure, and chemical alteration.

Answer: Here's an explanation of the requested environmental chemistry terms, drawing from the MCH-023 course context. **i) Soil profile** A soil profile is a vertical cross-section of the soil, extending from the surface down to the parent rock. It reveals distinct horizontal layers, called horizons, which differ in physical, chemical, and biological characteristics. These horizons, typically designated as O, A, B, C, and R, represent stages of soil development. The O horizon consists of organic matte...

Q2. Describe the reasons of soil alkalinity and the consequences of the same.

Key Points:

Soil alkalinity: pH above 7.0, common in arid/semi-arid climates.
Reasons: Accumulation of basic salts like CaCO₃ and Na₂CO₃.
Causes: Weathered parent material, high water tables, saline irrigation, high evaporation.
Consequence 1: Immobilization of micronutrients (Fe, Mn, Zn) for plants.

Answer: Soil alkalinity, characterized by a pH typically above 7.0, significantly impacts soil fertility and plant growth. It is predominantly observed in arid and semi-arid regions where low rainfall prevents the effective leaching of basic cations from the soil profile. The primary reasons for soil alkalinity include the accumulation of basic salts such as calcium carbonate (CaCO₃) and sodium carbonate (Na₂CO₃). These salts can originate from the weathering of parent rock material or be introduced th...

Q2. How is nitrogen important to the plants? Write the sources of this macronutrient to plants.

Key Points:

Soil alkalinity: pH above 7.0, common in arid/semi-arid climates.
Reasons: Accumulation of basic salts like CaCO₃ and Na₂CO₃.
Causes: Weathered parent material, high water tables, saline irrigation, high evaporation.
Consequence 1: Immobilization of micronutrients (Fe, Mn, Zn) for plants.

Answer: Soil alkalinity, characterized by a pH typically above 7.0, significantly impacts soil fertility and plant growth. It is predominantly observed in arid and semi-arid regions where low rainfall prevents the effective leaching of basic cations from the soil profile. The primary reasons for soil alkalinity include the accumulation of basic salts such as calcium carbonate (CaCO₃) and sodium carbonate (Na₂CO₃). These salts can originate from the weathering of parent rock material or be introduced th...

Q3. What is meant by the cation exchange capacity (CEC) of soils? What is the property of soil that determines the CEC of soils? How does CEC vary with pH?

Key Points:

CEC is the soil's capacity to hold exchangeable cations.
It arises from negative charges on clay minerals and organic matter.
Soil clay content and type significantly determine CEC.
Organic matter content is a major contributor to soil CEC.

Answer: The Cation Exchange Capacity (CEC) of soils represents the total capacity of soil particles to adsorb and hold exchangeable positively charged ions (cations) such as Ca²⁺, Mg²⁺, K⁺, and Na⁺. This critical property stems from the net negative charge present on the surface of soil colloids, primarily clay minerals and organic matter. CEC is a vital measure of soil fertility, indicating its ability to retain essential nutrient cations and prevent their leaching. The primary properties of soil tha...

Q3. Describe the distribution of the world's water resources among oceans, icecaps/ glaciers, groundwater, and surface water, providing approximate percentages.

Key Points:

CEC is the soil's capacity to hold exchangeable cations.
It arises from negative charges on clay minerals and organic matter.
Soil clay content and type significantly determine CEC.
Organic matter content is a major contributor to soil CEC.

Answer: The Cation Exchange Capacity (CEC) of soils represents the total capacity of soil particles to adsorb and hold exchangeable positively charged ions (cations) such as Ca²⁺, Mg²⁺, K⁺, and Na⁺. This critical property stems from the net negative charge present on the surface of soil colloids, primarily clay minerals and organic matter. CEC is a vital measure of soil fertility, indicating its ability to retain essential nutrient cations and prevent their leaching. The primary properties of soil tha...

Q4. Explain the importance of groundwater as a water resource in India. What are the problems in overusing ground water?

Key Points:

Groundwater is vital for 85% rural, 50% urban water, and 60% irrigation in India.
It's a reliable, less polluted source, crucial during dry seasons.
Overuse leads to declining water tables, increasing pumping expenses.
Excessive extraction causes land subsidence, damaging infrastructure.

Answer: Groundwater is an exceptionally critical water resource for India, serving as the primary source for domestic, agricultural, and industrial needs, particularly in rural areas and during periods of monsoon variability. It accounts for approximately 85% of rural water supply, 50% of urban water supply, and about 60% of the country's irrigation requirements. Its natural filtration process often makes it a safer drinking water source compared to surface water, and its subsurface storage provides res...

Q4. Define turbidity in water and explain its causes, measurement, and significance for water quality.

Key Points:

Groundwater is vital for 85% rural, 50% urban water, and 60% irrigation in India.
It's a reliable, less polluted source, crucial during dry seasons.
Overuse leads to declining water tables, increasing pumping expenses.
Excessive extraction causes land subsidence, damaging infrastructure.

Answer: Groundwater is an exceptionally critical water resource for India, serving as the primary source for domestic, agricultural, and industrial needs, particularly in rural areas and during periods of monsoon variability. It accounts for approximately 85% of rural water supply, 50% of urban water supply, and about 60% of the country's irrigation requirements. Its natural filtration process often makes it a safer drinking water source compared to surface water, and its subsurface storage provides res...

Q5. Briefly explain the factors affecting water quality.

Key Points:

Physical factors (temperature, turbidity) impact aquatic life and aesthetics.
Chemical factors include pH, dissolved oxygen, and various inorganic/organic pollutants.
Low dissolved oxygen signifies organic contamination, harming aquatic organisms.
Heavy metals, nitrates, phosphates, and pesticides are toxic chemical pollutants.

Answer: Water quality is a complex parameter influenced by various physical, chemical, and biological factors. Physical characteristics like temperature, turbidity, color, and odor significantly impact its suitability for different uses. For instance, elevated water temperature reduces dissolved oxygen, adversely affecting aquatic life, while high turbidity indicates suspended particles and poor clarity. Chemical factors are critical, encompassing pH, dissolved oxygen (DO), biochemical oxygen demand (B...

Q5. State the five "designated best uses" of water as per the Central Pollution Control Board (CPCB) classification and give one corresponding primary water quality criterion for each.

Key Points:

Physical factors (temperature, turbidity) impact aquatic life and aesthetics.
Chemical factors include pH, dissolved oxygen, and various inorganic/organic pollutants.
Low dissolved oxygen signifies organic contamination, harming aquatic organisms.
Heavy metals, nitrates, phosphates, and pesticides are toxic chemical pollutants.

Answer: Water quality is a complex parameter influenced by various physical, chemical, and biological factors. Physical characteristics like temperature, turbidity, color, and odor significantly impact its suitability for different uses. For instance, elevated water temperature reduces dissolved oxygen, adversely affecting aquatic life, while high turbidity indicates suspended particles and poor clarity. Chemical factors are critical, encompassing pH, dissolved oxygen (DO), biochemical oxygen demand (B...

Q6. What is meant by the atmospheric effect and the greenhouse effect?

Key Points:

Atmospheric effect: overall atmospheric influence on Earth's temperature regulation.
Greenhouse effect: specific mechanism of atmospheric warming.
GHGs absorb and re-emit outgoing infrared radiation, trapping heat.
Key greenhouse gases: CO₂, CH₄, N₂O, H₂O.

Answer: The atmospheric effect broadly refers to the overall influence of Earth's atmosphere on regulating the planet's temperature and climate. It describes how the atmosphere, through its composition and physical properties, modulates the balance between incoming solar radiation and outgoing terrestrial radiation. This general effect is fundamental in maintaining Earth's average surface temperature within a habitable range. The greenhouse effect is a specific and crucial component of the broader atm...

Q6. Explain how ozone layer depletion is related to global warming.

Key Points:

Atmospheric effect: overall atmospheric influence on Earth's temperature regulation.
Greenhouse effect: specific mechanism of atmospheric warming.
GHGs absorb and re-emit outgoing infrared radiation, trapping heat.
Key greenhouse gases: CO₂, CH₄, N₂O, H₂O.

Answer: The atmospheric effect broadly refers to the overall influence of Earth's atmosphere on regulating the planet's temperature and climate. It describes how the atmosphere, through its composition and physical properties, modulates the balance between incoming solar radiation and outgoing terrestrial radiation. This general effect is fundamental in maintaining Earth's average surface temperature within a habitable range. The greenhouse effect is a specific and crucial component of the broader atm...

Q7. How do the following factors affect the discharge of pollutants in the atmosphere?

i)) Atmospheric stability (100 words)
ii)) Temperature (100 words)
iii)) Precipitation (100 words)
iv)) Turbulence (100 words)
v)) Solar radiation (100 words)

Key Points:

Atmospheric stability (inversions) traps pollutants near surface, increasing concentration.
Temperature inversions hinder dispersion; high temperatures accelerate secondary pollutant formation.
Precipitation (wet deposition) removes pollutants from air but transfers them to land/water.
Turbulence (mechanical/thermal) promotes pollutant mixing and dilution, improving air quality.

Answer:

Q7. Distinguish between the following pairs giving examples:

i)) Stationary and Mobile sources of pollutants (125 words)
ii)) Indoor and Ambient air pollution (125 words)

Key Points:

Atmospheric stability (inversions) traps pollutants near surface, increasing concentration.
Temperature inversions hinder dispersion; high temperatures accelerate secondary pollutant formation.
Precipitation (wet deposition) removes pollutants from air but transfers them to land/water.
Turbulence (mechanical/thermal) promotes pollutant mixing and dilution, improving air quality.

Answer:

Q8. Name any two methods that are used for collecting gaseous samples and explain any one of these.

Key Points:

Evacuated Flask Method collects gas into a pre-evacuated inert container.
Adsorption on Solid Sorbent traps gaseous analytes onto a solid material.
Evacuated flask relies on pressure differential to draw in ambient air.
Canisters/flasks are typically inert stainless steel or treated glass.

Answer: Two primary methods used for collecting gaseous samples in environmental chemistry are the **Evacuated Flask Method** (also known as the Canister Method) and **Adsorption on Solid Sorbent**. The **Evacuated Flask Method** relies on collecting an air sample into a pre-evacuated, inert container. Prior to sampling, the container, often a specially treated stainless steel canister or a glass flask, is meticulously cleaned and evacuated to a very low pressure, typically below 0.05 torr, to create a...

Q8. Briefly explain the following terms:

i)) Dissolved Oxygen (DO) (125 words)
ii)) Biochemical Oxygen Demand (BOD) (125 words)

Key Points:

Evacuated Flask Method collects gas into a pre-evacuated inert container.
Adsorption on Solid Sorbent traps gaseous analytes onto a solid material.
Evacuated flask relies on pressure differential to draw in ambient air.
Canisters/flasks are typically inert stainless steel or treated glass.

Answer: Two primary methods used for collecting gaseous samples in environmental chemistry are the **Evacuated Flask Method** (also known as the Canister Method) and **Adsorption on Solid Sorbent**. The **Evacuated Flask Method** relies on collecting an air sample into a pre-evacuated, inert container. Prior to sampling, the container, often a specially treated stainless steel canister or a glass flask, is meticulously cleaned and evacuated to a very low pressure, typically below 0.05 torr, to create a...

Q9. Discuss the method of aeration in the treatment of daily wastes. Also give the problems associated with it.

Key Points:

Aeration supplies oxygen to microorganisms for aerobic degradation of organic waste.
It reduces Biochemical Oxygen Demand (BOD) by converting pollutants to stable compounds.
Methods include mechanical aerators and diffused air systems in aeration basins.
Major problem: High energy consumption for oxygen supply.

Answer: Aeration is a crucial secondary treatment method for daily (domestic) wastes, primarily enhancing biological degradation. It involves introducing air or oxygen into wastewater to supply oxygen to aerobic microorganisms. These microbes then efficiently break down organic pollutants present in the wastewater, converting them into stable inorganic compounds like carbon dioxide and water, thereby reducing the Biochemical Oxygen Demand (BOD). This process is typically implemented in aeration basins,...

Q9. Give the characteristics of an ideal pesticide.

Key Points:

Aeration supplies oxygen to microorganisms for aerobic degradation of organic waste.
It reduces Biochemical Oxygen Demand (BOD) by converting pollutants to stable compounds.
Methods include mechanical aerators and diffused air systems in aeration basins.
Major problem: High energy consumption for oxygen supply.

Answer: Aeration is a crucial secondary treatment method for daily (domestic) wastes, primarily enhancing biological degradation. It involves introducing air or oxygen into wastewater to supply oxygen to aerobic microorganisms. These microbes then efficiently break down organic pollutants present in the wastewater, converting them into stable inorganic compounds like carbon dioxide and water, thereby reducing the Biochemical Oxygen Demand (BOD). This process is typically implemented in aeration basins,...

Q10. In which form the phosphorous occurs in sewage? Also, briefly explain the methods of removing it.

Key Points:

Phosphorus in sewage exists as orthophosphates, polyphosphates, and organic forms.
Orthophosphates (PO₄³⁻) are most prevalent, from human waste and detergents.
Chemical precipitation uses metal salts (alum, ferric chloride) to form insoluble precipitates.
Insoluble aluminum or ferric phosphates are removed via sedimentation.

Answer: In sewage, phosphorus primarily exists in various forms, including inorganic orthophosphates (PO₄³⁻), polyphosphates, and organically bound phosphorus. Orthophosphates are the most prevalent and biologically available form, originating from human excreta, food waste, and phosphorus-containing detergents. Polyphosphates are often found in detergents, while organic phosphorus is part of cellular material. Removal of phosphorus from sewage is crucial to prevent eutrophication. One common method is...

Q10. How are Pathogenic bacteria transmitted in water? List any five diseases transmitted by them.

Key Points:

Phosphorus in sewage exists as orthophosphates, polyphosphates, and organic forms.
Orthophosphates (PO₄³⁻) are most prevalent, from human waste and detergents.
Chemical precipitation uses metal salts (alum, ferric chloride) to form insoluble precipitates.
Insoluble aluminum or ferric phosphates are removed via sedimentation.

Answer: In sewage, phosphorus primarily exists in various forms, including inorganic orthophosphates (PO₄³⁻), polyphosphates, and organically bound phosphorus. Orthophosphates are the most prevalent and biologically available form, originating from human excreta, food waste, and phosphorus-containing detergents. Polyphosphates are often found in detergents, while organic phosphorus is part of cellular material. Removal of phosphorus from sewage is crucial to prevent eutrophication. One common method is...

MCH-023 Solved Assignment — January 2026 / July 2026

ENVIRONMENTAL CHEMISTRY | IGNOU Master of Science in Chemistry Programme (MSCCHEM)

MCH-023—January 2026 / July 2026

ENVIRONMENTAL CHEMISTRY

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MCH-023 Assignment Questions — January 2026

Q1. Explain the following in brief.

Q1. How is the soil texture analysis done? Describe in brief.

Q2. Describe the reasons of soil alkalinity and the consequences of the same.

Q2. How is nitrogen important to the plants? Write the sources of this macronutrient to plants.

Q3. What is meant by the cation exchange capacity (CEC) of soils? What is the property of soil that determines the CEC of soils? How does CEC vary with pH?

Q3. Describe the distribution of the world's water resources among oceans, icecaps/ glaciers, groundwater, and surface water, providing approximate percentages.

Q4. Explain the importance of groundwater as a water resource in India. What are the problems in overusing ground water?

Q4. Define turbidity in water and explain its causes, measurement, and significance for water quality.

Q5. Briefly explain the factors affecting water quality.

Q5. State the five "designated best uses" of water as per the Central Pollution Control Board (CPCB) classification and give one corresponding primary water quality criterion for each.

Q6. What is meant by the atmospheric effect and the greenhouse effect?

Q6. Explain how ozone layer depletion is related to global warming.

Q7. How do the following factors affect the discharge of pollutants in the atmosphere?

Q7. Distinguish between the following pairs giving examples:

Q8. Name any two methods that are used for collecting gaseous samples and explain any one of these.

Q8. Briefly explain the following terms:

Q9. Discuss the method of aeration in the treatment of daily wastes. Also give the problems associated with it.

Q9. Give the characteristics of an ideal pesticide.

Q10. In which form the phosphorous occurs in sewage? Also, briefly explain the methods of removing it.

Q10. How are Pathogenic bacteria transmitted in water? List any five diseases transmitted by them.