If you are sitting for the IGNOU Term-End Examination and need reliable, well-structured solved answers for AEC-01, you have found the right place.

Unnati Education has prepared a complete AEC-01 Environmental Chemistry Question Paper of December 2025. This is made for BSC and BA students enrolled in the Application Oriented Course programme.

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What is AEC-01 December 2025 Question Paper?

The AEC-01 December 2025 question paper is the official IGNOU Term-End Examination paper for Environmental Chemistry, carrying 100 marks across five sections, covering soil, water, air pollution, and analytical techniques.

AEC-01 is part of the Application Oriented Course offered under IGNOU's BSC and BA programmes. The December 2025 examination was held for a duration of 3 hours. All questions are compulsory in Q1, while Q2 to Q4 ask students to attempt any four out of six. Q5 is a short notes section where students must write on any four topics. The paper tests both theoretical understanding and applied knowledge of environmental chemistry.

About IGNOU AEC-01 — Environmental Chemistry

AEC-01 is one of those subjects that connects chemistry directly to real-world problems. You study how pollutants behave in soil, how water bodies get contaminated, how air quality degrades, and what analytical tools scientists use to measure all of this. It is genuinely useful knowledge, not just bookwork.

Most students find the analytical techniques section — things like chromatography, UV-Vis spectrometry, and potentiometry — a bit tricky at first. That is where good solved examples really help. Once you see how an answer is structured, the concepts click much faster. The subject also covers industrial waste treatment, which is increasingly relevant in today's environmental context.

AEC-01 December 2025 — Question Paper Pattern and Marks Breakdown

Q1 is divided into three parts. Part (a) is fill in the blanks, attempt any five, 1 mark each. Part (b) is definitions, attempt any five, 1 mark each. Part (c) is short answers, attempt any five, 2 marks each. Q1 total is 20 marks. Q2, Q3, and Q4 each carry 20 marks, and you must attempt any four questions out of six in each section. Q5 is short notes, attempt any four, 5 marks each, totalling 20 marks. The full paper adds up to 100 marks and must be completed in 3 hours.

All Questions — AEC-01 December 2025 Question Paper (Complete List)

Below is the complete question paper exactly as set in the IGNOU December 2025 examination. These are the actual questions your solved paper addresses.

Question 1 (a) Fill in the blanks in any five of the following: (i) Soil organisms are divided into two groups ............ and .......... (ii) ............. is that part of precipitation which soaks into soil and keeps moving underground. (iii) The temperature of a water body decides to a large extent its ................. activities. (iv) The lowest portion of the atmosphere is called .............. . (v) An aerosol of liquid droplets near the ground is called as ............. . (vi) Substances that drain out moisture out of the plants causing them to dry are called ............... .

Question 1 (b) Define any five of the following: (i) Lapse rate (ii) Dissolved oxygen (iii) Total Suspended Solids (iv) Pesticides (v) Rodenticide (vi) Global Warming Potential

Question 1 (c) Answer any five of the following: (i) Explain coalescence. (ii) What is the effective stack height? How does it affect the down wash of pollutants? (iii) List the four general foliar markings that indicate the possible presence of air pollutants. (iv) List two common household substances that contribute to hazardous wastes. (v) Explain the principle of chromatography. (vi) Write any two advantages of the double beam photometer over single beam photometer.

Question 2 Answer any four of the following questions: (i) Discuss the effects of soil aeration on soil colour, gas exchange and plant nutrient availability. How do redox reactions and soil aeration impact the growth of plants? (ii) How does soil texture affect plant's availability of moisture and soil holding capacity? Explain with suitable examples. (iii) Leguminous crop grown under phosphate deficiency conditions may suffer from N deficiency as well. Explain. (iv) Describe the process of softening and deionization of water using ion exchange resins. (v) What is the role of Dissolved Oxygen (DO) in assessing water pollution? How does this parameter indicate the aquatic health? What are their measurement procedures? (vi) State the advantages of biomonitoring over chemical monitoring.

Question 3 Answer any four of the following questions: (i) Describe the principle of potentiometry. Illustrate with an example, how e.m.f. of a galvanic cell is measured. (ii) Explain the principle of UV-Vis spectrometry. Draw the order of energy for various types of molecular orbitals and electronic transitions. (iii) Describe the Desal process for the treatment of brackish water with the help of a suitable diagram. (iv) Describe the activated sludge process of aerobic biological treatment of industrial waste. (v) What is the full form of AQI? How is it computed? Explain its significance in reporting the pollutant standard index. (vi) What are the sources of heavy metals in water pollution? How do these metals accumulate in the environment? Explain their potential risks on the environment and human health.

Question 4 Answer any four of the following questions: (i) What is the impact of high nitrate concentrations in drinking water on human health? What measures can be taken to prevent nitrate contamination in drinking water? (ii) What are the advantages and limitations of drip irrigation compared to surface and sprinklers method? Explain. (iii) Describe the effect of temperature and the presence of nitrifying bacteria on the BOD. How can interference from nitrification be addressed? (iv) List any five ways by which pesticides may reach the soil. (v) What are the major pollutants present in the effluents from pulp and paper industry? Write their sources and explain how do they affect water bodies and aquatic life. (vi) What techniques are used to estimate the numbers and kinds of soil micro-organisms? Explain briefly.

Question 5 Write short notes on any four of the following: (i) Complexometric titrations (ii) Thin layer chromatography (iii) Henry's law (iv) The membrane filter test (v) Tannery waste treatment (vi) Photochemical smog

AEC-01 Syllabus Topics Covered in December 2025 Paper

The December 2025 paper touches every major area of the AEC-01 syllabus. Soil chemistry features heavily, including aeration, texture, nutrient availability, and microbial activity. Water treatment topics include ion exchange, dissolved oxygen, BOD, desalination, and heavy metal contamination. Air pollution questions cover the atmosphere's structure, aerosols, AQI, and photochemical smog. Analytical techniques include chromatography, UV-Vis spectrometry, potentiometry, and photometry. Environmental monitoring covers both chemical and biological methods. Industrial waste sections address pulp and paper effluents, tannery waste, and activated sludge processes.

Sample Answer Preview — See How We Solve AEC-01 Questions

Here is a quick example of how our solved paper approaches Question 1(a)(iv):

Answer: The lowest portion of the atmosphere is called the troposphere.

And here is the opening of a full answer for Q2(v) on Dissolved Oxygen:

Dissolved oxygen refers to the amount of oxygen dissolved in a water body, and it serves as one of the most reliable indicators of aquatic health. A high DO level generally signals a clean, well-oxygenated water body capable of supporting fish and other aquatic life. When organic pollutants enter water, microbial decomposition consumes oxygen, causing DO levels to fall sharply...

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How to Write High-Scoring Answers in AEC-01 — Exam Tips

Start every definition question with a clean one-line definition before expanding. Examiners check whether you know the core meaning first. For long answers, use a brief introduction, a structured explanation with relevant chemical or environmental examples, and a short conclusion. In questions on analytical techniques, always mention the principle first, then describe the procedure. Wherever possible, include a labelled diagram — even a rough sketch with proper labels adds marks. Keep your language precise. IGNOU markers reward clarity over length, so a focused 200-word answer often scores better than a vague 400-word one.

Who Should Use This AEC-01 December 2025 Solved Paper?

This solved paper is most useful for BSC and BA students registered under IGNOU's Application Oriented Course programme who appeared or plan to appear for the AEC-01 exam. It is equally helpful for students who are repeating the examination and want to understand where their previous answers fell short. Environmental science learners who want to build conceptual clarity alongside exam preparation will also find the detailed explanations genuinely useful.

Why This Is Better Than Free AEC-01 PDFs and Telegram Files

Free PDFs floating on Telegram are often incomplete, outdated, or simply wrong. Some contain answers from previous years' papers that do not match the current question set. Unnati Education's solved paper is written specifically for the December 2025 question paper, with answers that match each question exactly. Every answer follows proper IGNOU exam format. Diagrams are included where the question demands them. The language is clear enough to read and understand quickly, even the night before your exam. That is the difference between a resource that helps you revise and one that just adds to your confusion.

Student Reviews — AEC-01 Solved Paper by Unnati Education

Priya Singh, BSC IGNOU Delhi: "I had been struggling with the analytical techniques section for weeks. The solved paper explained potentiometry and UV-Vis in a way that finally made sense. Cleared AEC-01 in December 2025."

Rahul Mehta, BA IGNOU Jaipur: "Got the paper on WhatsApp within an hour of requesting. All questions from the December 2025 paper were covered. Highly recommended for last-minute revision."

Anita Verma, BSC IGNOU Mumbai: "The AQI question and the heavy metals answer were perfectly structured. I used them as templates and scored well. Worth every rupee."

How to Get the AEC-01 December 2025 Solved Paper — Step by Step

Step 1: Contact Unnati Education via the WhatsApp number or order button on this page. Step 2: Share your course code (AEC-01) and confirm you need the December 2025 solved paper. Step 3: Receive your complete solved paper instantly on WhatsApp or email. That is it. No lengthy forms, no waiting days for delivery.

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Frequently Asked Questions — AEC-01 December 2025

What is AEC-01 in IGNOU?

AEC-01 is Environmental Chemistry, an Application Oriented Course offered under IGNOU's BSC and BA programmes. It covers soil chemistry, water pollution, air pollution, analytical techniques, and environmental monitoring. The course is designed to give students practical knowledge of how chemistry applies to environmental problems and assessment.

How many marks does the AEC-01 December 2025 paper carry?

The AEC-01 December 2025 question paper carries a total of 100 marks. It is divided into five sections. Q1 carries 20 marks and is fully compulsory. Q2, Q3, and Q4 each carry 20 marks and require students to attempt any four out of six questions. Q5 is short notes for 20 marks, any four out of six topics.

Are all questions compulsory in AEC-01?

In Q1, all parts are compulsory though you choose any five within each sub-section. In Q2, Q3, and Q4, you must attempt any four questions out of six. In Q5, you write short notes on any four topics. So while you have choice within sections, you must attempt all five question blocks to complete the paper.

What topics are covered in AEC-01?

AEC-01 covers soil science including aeration, texture, and nutrient availability. It also covers water chemistry, dissolved oxygen, BOD, water treatment processes, and heavy metal contamination. Air pollution topics include the atmosphere's structure, AQI, and photochemical smog. Analytical techniques such as chromatography, UV-Vis spectrometry, and potentiometry are also included.

What is AQI and why is it asked in AEC-01?

AQI stands for Air Quality Index. It is a standardised scale used by environmental agencies to report how polluted the air is on a given day. In AEC-01, it appears in the context of air pollution monitoring and the pollutant standard index. Understanding AQI is core to the environmental monitoring section of the syllabus and is frequently examined.

About Unnati Education — IGNOU Study Material Experts

Unnati Education has been helping IGNOU students prepare for Term-End Examinations for several years. We focus exclusively on IGNOU study material — solved papers, assignments, guess papers, and exam-ready notes. Our content is prepared by writers who have studied the IGNOU pattern closely and understand what works in examinations. We do not outsource or recycle generic content. Every solved paper is written fresh for the specific question paper of that examination cycle. Students across India trust Unnati Education because we deliver accurate, structured, and genuinely useful academic resources on time.

Explore More IGNOU AEC Solved Papers and Study Material

Looking for more help beyond AEC-01? Unnati Education also provides solved papers for other AEC courses including AEC-02. We also offer IGNOU assignment solutions, guess papers for upcoming exams, and admission guidance for new students. Browse our full catalogue of Application Oriented Course materials to find everything you need in one place.

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