Chemistry Objective Questions and Answers: Environmental Chemistry
Access targeted multiple-choice questions for Environmental Chemistry designed to align with the latest JEE academic syllabus for JEE Chemistry. These objective practice sets help students evaluate their conceptual understanding and improve exam readiness.
Download Environmental Chemistry MCQs with Answers
Access the complete set of multiple-choice questions for Environmental Chemistry below. This focused format allows students to isolate specific topics for thorough review and uninterrupted practice alongside official JEE textbooks.
Multiple Choice Questions
(a) CO2
(b) CO
(c) NO2
(d) SO2
Show Answer & Explanation
Answer: (b) CO
Explanation:
1. Carbon monoxide forms carboxyhaemoglobin, which is much more stable than oxyhaemoglobin, so oxygen transport is reduced.
Teacher's Note:
1. Carbon monoxide poisoning produces headache and weak eyesight.
(a) ocean water
(b) soil bacteria
(c) green plants
(d) ozone
Show Answer & Explanation
Answer: (b) soil bacteria
Explanation:
1. Soil microorganisms convert CO to CO2, so CO does not accumulate.
Teacher's Note:
1. This is why CO levels do not rise as much as emissions suggest.
(a) CO
(b) SO2
(c) PAN
(d) soot
Show Answer & Explanation
Answer: (c) PAN
Explanation:
1. PAN forms in the air from nitrogen oxides and hydrocarbons in sunlight; the others are emitted directly.
Teacher's Note:
1. Ozone and acid rain are also secondary pollutants.
(a) \( N_2 + O_2 \to 2NO \) at high temperature
(b) \( 2NO_2 \to N_2O_4 \)
(c) \( NH_3 + O_2 \to NO \) at room temperature
(d) \( N_2O \to N_2 + O \)
Show Answer & Explanation
Answer: (a) \( N_2 + O_2 \to 2NO \) at high temperature
Explanation:
1. At about 1500 K nitrogen and oxygen of the air react to form NO, which is oxidised to \( NO_2 \).
Teacher's Note:
1. Lightning produces NO in the same way.
(a) is an oxidising smog formed in sunlight
(b) occurs in cool, humid climates and contains SO2 and smoke (a reducing smog)
(c) contains PAN and ozone
(d) occurs only in hot dry places
Show Answer & Explanation
Answer: (b) occurs in cool, humid climates and contains SO2 and smoke (a reducing smog)
Explanation:
1. London smog is formed from sulphur oxides and smoke in cool humid weather; photochemical smog needs sunlight, NOx and hydrocarbons.
Teacher's Note:
1. Classical smog is reducing; photochemical smog is oxidising.
(a) Ozone
(b) PAN
(c) Formaldehyde
(d) Sulphur dioxide as the main component
Show Answer & Explanation
Answer: (d) Sulphur dioxide as the main component
Explanation:
1. Photochemical smog contains ozone, NO, acrolein, formaldehyde and PAN. High SO2 is characteristic of classical smog.
Teacher's Note:
1. Think of NOx and hydrocarbons in sunlight.
(a) \( CH_3COOONO_2 \)
(b) \( CH_3CONO_2 \)
(c) \( CH_3COONO \)
(d) \( CH_3CH_2ONO_2 \)
Show Answer & Explanation
Answer: (a) \( CH_3COOONO_2 \)
Explanation:
1. PAN is \( CH_3\text{-}CO\text{-}OO\text{-}NO_2 \), peroxyacetyl nitrate.
Teacher's Note:
1. It causes eye irritation.
(a) particulate matter
(b) carbon dioxide
(c) argon
(d) nitrogen
Show Answer & Explanation
Answer: (a) particulate matter
Explanation:
1. Particulate matter, ozone and hydrogen peroxide promote this oxidation.
Teacher's Note:
1. SO3 then reacts with water to give H2SO4.
(a) less than 5.6
(b) 7
(c) greater than 8
(d) exactly 6.5
Show Answer & Explanation
Answer: (a) less than 5.6
Explanation:
1. Normal rain is about pH 5.6 due to dissolved CO2; acid rain is more acidic than that.
Teacher's Note:
1. The main acid precursors are SO2 and NOx.
(a) marble \( (CaCO_3) \) reacts with \( H_2SO_4 \)
(b) marble reacts with \( CO_2 \) to form a soluble salt
(c) sandstone dissolves in water
(d) ozone oxidises marble
Show Answer & Explanation
Answer: (a) marble \( (CaCO_3) \) reacts with \( H_2SO_4 \)
Explanation:
1. \( CaCO_3 + H_2SO_4 \to CaSO_4 + H_2O + CO_2 \).
Teacher's Note:
1. The Mathura refinery SO2 is a suspected source.
(a) \( NO + O_3 \to NO_2 + O_2 \) followed by \( NO_2 + O \to NO + O_2 \)
(b) \( NO + O_2 \to NO_2 \) only
(c) \( NO_2 \to NO + O_3 \)
(d) \( 2NO \to N_2 + O_2 \)
Show Answer & Explanation
Answer: (a) \( NO + O_3 \to NO_2 + O_2 \) followed by \( NO_2 + O \to NO + O_2 \)
Explanation:
1. NO is regenerated in the second step, so it acts as a catalyst in destroying ozone.
Teacher's Note:
1. One NO molecule can destroy many ozone molecules.
(a) fluorine atoms
(b) chlorine free radicals
(c) carbon atoms
(d) hydrogen atoms
Show Answer & Explanation
Answer: (b) chlorine free radicals
Explanation:
1. UV light splits C-Cl bonds: \( Cl\cdot + O_3 \to ClO\cdot + O_2 \) and \( ClO\cdot + O \to Cl\cdot + O_2 \). The chlorine atom is regenerated.
Teacher's Note:
1. The C-F bond is too strong to be broken by stratospheric UV.
(a) polar stratospheric clouds provide surfaces for the release of active chlorine
(b) there is high temperature in the stratosphere
(c) nitrogen dioxide is abundant
(d) there is no sunlight
Show Answer & Explanation
Answer: (a) polar stratospheric clouds provide surfaces for the release of active chlorine
Explanation:
1. In winter, polar stratospheric clouds hold chlorine nitrate, which is hydrolysed to HOCl; sunlight in spring releases Cl atoms which attack ozone.
Teacher's Note:
1. In summer NO2 and CH4 form chlorine sinks.
(a) CO2
(b) CH4
(c) N2
(d) O3
Show Answer & Explanation
Answer: (c) N2
Explanation:
1. Nitrogen does not absorb infrared radiation; CO2, methane, ozone, CFCs, nitrous oxide and water vapour do.
Teacher's Note:
1. Diatomic homonuclear gases (N2, O2) are not greenhouse gases.
(a) 2 ppm
(b) 6 ppm
(c) 10 ppm
(d) 20 ppm
Show Answer & Explanation
Answer: (b) 6 ppm
Explanation:
1. Fish growth is inhibited below 6 ppm of dissolved oxygen; cold water can hold up to about 10 ppm.
Teacher's Note:
1. Oxygen is added by diffusion and by photosynthesis in daylight.
(a) less than 5 ppm
(b) about 17 ppm
(c) more than 100 ppm
(d) exactly zero
Show Answer & Explanation
Answer: (a) less than 5 ppm
Explanation:
1. Clean water has BOD below 5 ppm and highly polluted water has BOD of 17 ppm or more.
Teacher's Note:
1. A higher BOD indicates more organic pollution.
(a) COD is always lower than BOD
(b) COD is always higher than BOD
(c) COD and BOD are equal
(d) COD does not use an oxidant
Show Answer & Explanation
Answer: (b) COD is always higher than BOD
Explanation:
1. COD measures oxidation of all organic matter with potassium dichromate, biodegradable and non-biodegradable, so it is greater than BOD.
Teacher's Note:
1. BOD measures only matter oxidised by bacteria.
(a) blue baby syndrome
(b) fluorosis
(c) Minamata disease
(d) itai-itai disease
Show Answer & Explanation
Answer: (a) blue baby syndrome
Explanation:
1. Nitrate converts haemoglobin to methaemoglobin in infants (methaemoglobinemia).
Teacher's Note:
1. The maximum permissible nitrate level is 50 ppm.
(a) 1 ppm
(b) 10 ppm
(c) 50 ppm
(d) 0.001 ppm
Show Answer & Explanation
Answer: (a) 1 ppm
Explanation:
1. About 1 ppm hardens tooth enamel; above 2 ppm causes mottling and above 10 ppm harms bones.
Teacher's Note:
1. Fluoride converts hydroxyapatite to the harder fluorapatite.
(a) 1 and 3
(b) 5.5 and 9.5
(c) 10 and 12
(d) 3 and 5
Show Answer & Explanation
Answer: (b) 5.5 and 9.5
Explanation:
1. Standard drinking water has pH 5.5 to 9.5.
Teacher's Note:
1. Low pH increases the solubility of toxic metal ions.
(a) 50 ppb
(b) 50 ppm
(c) 5 ppm
(d) 0.5 ppt
Show Answer & Explanation
Answer: (a) 50 ppb
Explanation:
1. The limit is 50 ppb (in the standards given here).
Teacher's Note:
1. Acidic water in lead pipes is liable to get contaminated.
(a) phosphates from detergents and fertilisers
(b) chlorides
(c) carbon monoxide
(d) heavy metals
Show Answer & Explanation
Answer: (a) phosphates from detergents and fertilisers
Explanation:
1. Phosphate encourages algal growth, which later reduces dissolved oxygen.
Teacher's Note:
1. This hinders higher life forms such as fish.
(a) Cd, Pb and Hg
(b) Na, K and Ca
(c) N2, O2 and H2
(d) Cl-, F- and I-
Show Answer & Explanation
Answer: (a) Cd, Pb and Hg
Explanation:
1. The body cannot excrete these heavy metals, so concentration builds up with time.
Teacher's Note:
1. They damage the kidneys, liver and nervous system.
(a) Liquid carbon dioxide with a detergent
(b) Benzene
(c) Carbon tetrachloride
(d) Chloroform
Show Answer & Explanation
Answer: (a) Liquid carbon dioxide with a detergent
Explanation:
1. Liquid CO2 with a suitable detergent is non-toxic and does not contaminate ground water.
Teacher's Note:
1. Hydrogen peroxide is used for bleaching clothes.
(a) it gives water as the by-product and is less polluting
(b) it is more expensive
(c) it is a stronger acid
(d) it contains chlorine
Show Answer & Explanation
Answer: (a) it gives water as the by-product and is less polluting
Explanation:
1. With a suitable catalyst H2O2 bleaches paper and leaves only water and oxygen.
Teacher's Note:
1. Chlorine bleaching produces chlorinated organic pollutants.
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Multiple Choice Questions (MCQs) for JEE Chemistry Environmental Chemistry
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FAQs
You can get most exhaustive JEE Chemistry Environmental Chemistry MCQs Set 08 for free on StudiesToday.com. These MCQs for JEE Chemistry are updated for the 2026-27 academic session as per JEE examination standards.
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By solving our JEE Chemistry Environmental Chemistry MCQs Set 08, JEE students can improve their accuracy and speed which is important as objective questions provide a chance to secure 100% marks in the Chemistry.
Yes, Chemistry MCQs for JEE have answer key and brief explanations to help students understand logic behind the correct option as its important for 2026 competency-focused JEE exams.
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