Environmental Chemistry JENPAS MCQ & Practice Questions

Practice Environmental Chemistry MCQs for JENPAS Chemistry with answers, explanations, chapter revision and related ChemNexa mock tests.

Environmental Chemistry Revision Guide for JENPAS Chemistry

Environmental Chemistry is part of JENPAS Chemistry preparation. A strong revision plan should combine concept review with exam-style questions so that definitions, relationships, calculations and exceptions are recalled accurately.

Use the sample MCQs on this page to check understanding, then attempt the related ChemNexa tests for broader practice. When an answer is wrong, review the explanation and return to the underlying concept before attempting another set.

Important Topics

Core definitions and principles
Important equations or relationships
Common applications and examples
Frequently confused concepts
Exam-style multiple-choice questions
Error review and targeted revision

Revision Tip

Create a one-page summary of trends, structures, reactions, exceptions and key terminology for Environmental Chemistry, then test recall with mixed MCQs.

What to practise in Environmental Chemistry

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Environmental Chemistry before attempting MCQs.

Exam-style MCQs

Use chapter-focused multiple-choice practice to improve accuracy, recall and application for JENPAS Chemistry.

Performance Practice

Attempt ChemNexa tests, review results and return to weak areas for another round of targeted revision.

Top 20 Environmental Chemistry MCQs with Answers

These public questions are selected from the exact Environmental Chemistry chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

1. The major anthropogenic greenhouse gas released by fossil-fuel combustion is:

A. N2
B. He
C. CO2
D. O2

Answer: C

Explanation: Combustion of carbon-containing fuels releases carbon dioxide.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

2. The greenhouse effect occurs because certain gases absorb:

A. Radio waves only
B. Outgoing infrared radiation
C. All visible light
D. Only ultraviolet radiation

Answer: B

Explanation: Greenhouse gases absorb and re-emit terrestrial infrared radiation.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

3. Methane is an important greenhouse gas with formula:

A. CH4
B. CH3OH
C. CO
D. C2H6

Answer: A

Explanation: Methane is CH4.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

4. Global warming refers to:

A. Daily weather variation
B. Only ozone depletion
C. Ocean tides
D. Long-term rise in average global temperature

Answer: D

Explanation: Global warming is the long-term increase in Earth's mean surface temperature.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

5. The stratospheric ozone layer mainly protects life by absorbing:

A. Radio waves
B. Visible green light only
C. Ultraviolet radiation
D. Microwaves

Answer: C

Explanation: Ozone absorbs biologically harmful UV radiation.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

6. Ozone depletion has been strongly linked with:

A. Water vapour only
B. CFCs
C. CO2 only
D. N2

Answer: B

Explanation: CFC photolysis releases chlorine radicals that catalyse ozone destruction.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

7. A chlorine radical can destroy many ozone molecules because it acts:

A. Catalytically
B. As a precipitant
C. As a solvent
D. As a buffer

Answer: A

Explanation: Chlorine radicals are regenerated during the ozone-destruction cycle.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

8. Photochemical smog is associated especially with:

A. Only NaCl aerosol
B. Only CO2 and water
C. Nitrogen gas alone
D. NOx and hydrocarbons under sunlight

Answer: D

Explanation: Sunlight drives reactions of NOx and VOCs to form oxidants.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

9. A major oxidant in photochemical smog is:

A. Nitrogen
B. Helium
C. Ozone
D. Hydrogen

Answer: C

Explanation: Ground-level ozone is a major component of photochemical smog.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

10. Classical reducing smog is strongly associated with:

A. Methane only
B. SO2 and particulates
C. O3 only
D. CFCs only

Answer: B

Explanation: Sulfurous smog results from coal combustion, sulfur dioxide and particulate matter.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

11. Acid rain is mainly associated with atmospheric oxidation of:

A. SO2 and NOx
B. O2 and N2
C. CH4 and H2
D. He and Ne

Answer: A

Explanation: Sulfur and nitrogen oxides form sulfuric and nitric acids.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

12. Acid rain can damage limestone monuments because acids react with:

A. SiO2 only
B. NaCl only
C. Graphite
D. CaCO3

Answer: D

Explanation: Carbonate stone reacts with acidic precipitation.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

13. Carbon monoxide is dangerous because it binds strongly with:

A. Silica
B. NaCl
C. Haemoglobin
D. Cellulose

Answer: C

Explanation: CO forms carboxyhaemoglobin and impairs oxygen transport.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

14. Fine particulate matter primarily affects the:

A. Ocean salinity
B. Respiratory system
C. Atomic nucleus
D. Magnetic field

Answer: B

Explanation: Fine particles can penetrate deep into the respiratory tract.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

15. Catalytic converters in automobiles help reduce:

A. CO, hydrocarbons and NOx
B. Only O2
C. Only N2
D. Only water vapour

Answer: A

Explanation: Converters oxidise CO/hydrocarbons and reduce nitrogen oxides.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

16. Lead-free petrol was promoted partly to reduce exposure to:

A. Calcium compounds
B. Sodium chloride
C. Silica
D. Lead compounds

Answer: D

Explanation: Tetraethyl lead was a major source of lead pollution.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

17. BOD is a measure related to oxygen required by:

A. Ozone formation
B. Only fish respiration
C. Microorganisms decomposing biodegradable organic matter
D. Metals dissolving in water

Answer: C

Explanation: Biochemical oxygen demand reflects microbial oxygen consumption.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

18. A high BOD value generally indicates:

A. High dissolved oxygen necessarily
B. High biodegradable organic pollution
C. Exceptionally pure water
D. No microorganisms

Answer: B

Explanation: More biodegradable waste causes greater microbial oxygen demand.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

19. Eutrophication is commonly promoted by excess:

A. Nitrate and phosphate nutrients
B. Noble gases
C. Sand only
D. NaCl only

Answer: A

Explanation: Nutrient enrichment stimulates excessive algal growth.

JENPAS Chemistry · Environmental Chemistry · Very Very Hard

20. An algal bloom can lower dissolved oxygen after decay because:

A. Photosynthesis increases forever
B. Water becomes distilled
C. Nitrogen becomes oxygen
D. Microbial decomposition consumes oxygen

Answer: D

Explanation: Decomposition of biomass raises oxygen demand.