JEE Chemistry Environmental Chemistry MCQs Set 16

Practice MCQs for JEE Chemistry Environmental Chemistry

Explore reliable objective questions for Environmental Chemistry tailored for JEE learners. Utilizing these Chemistry multiple-choice formats ensures thorough preparation and strengthens problem-solving speed for upcoming school assessments.

Access Environmental Chemistry Questions and Solutions

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

Question 1: Which of the following is wrong with respect to our responsibility as human beings to protect the environment?
(a) Restricting the use of vehicles
(b) Avoiding the use of floodlighted facilities
(c) Setting up compost tins in gardens
(d) Using plastic bags
Show Answer & Explanation

Answer: (d) Using plastic bags

Explanation:
1. Plastic bags are non-biodegradable and remain in the environment for a very long time.
2. The other three actions reduce pollution and waste.

Teacher's Note:
1. Reduce, reuse and recycle: plastics are a major non-biodegradable pollutant.

Question 2: The maximum prescribed concentration of copper in drinking water is:
(a) 5 ppm
(b) 0.5 ppm
(c) 0.05 ppm
(d) 3 ppm
Show Answer & Explanation

Answer: (d) 3 ppm

Explanation:
1. According to the WHO and EPA, the maximum allowable concentration of copper in drinking water is 3 ppm.
2. For reference, Zn is 5 ppm, Fe is 0.2 ppm and Mn is 0.05 ppm.

Teacher's Note:
1. Remember the limits: Cu 3, Zn 5, Fe 0.2, Mn 0.05 ppm.

Question 3: Excessive release of CO₂ into the atmosphere results in:
(a) formation of smog
(b) depletion of ozone
(c) polar vortex
(d) global warming
Show Answer & Explanation

Answer: (d) global warming

Explanation:
1. CO₂ is a greenhouse gas that traps infrared radiation.
2. This raises the temperature of the earth, i.e. global warming.

Teacher's Note:
1. Main greenhouse gases are CO₂, CH₄, N₂O, CFCs and water vapour.

Question 4: The regions of the atmosphere where clouds form and where we live, respectively, are:
(a) stratosphere and stratosphere
(b) troposphere and troposphere
(c) troposphere and stratosphere
(d) stratosphere and troposphere
Show Answer & Explanation

Answer: (b) troposphere and troposphere

Explanation:
1. The lowest region, the troposphere (up to about 10 km), contains air, water vapour and dust.
2. Clouds form there and we also live there.

Teacher's Note:
1. Weather phenomena occur in the troposphere.

Question 5: Air pollution that occurs in sunlight is:
(a) acid rain
(b) oxidising smog
(c) fog
(d) reducing smog
Show Answer & Explanation

Answer: (b) oxidising smog

Explanation:
1. Photochemical (oxidising or Los Angeles) smog is formed from NOx and hydrocarbons in the presence of sunlight.
2. Reducing smog (London smog) forms in cold, humid weather with SO₂.

Teacher's Note:
1. Photochemical smog contains O₃, PAN and aldehydes.

Question 6: The correct set of species responsible for photochemical smog is:
(a) N₂, NO₂ and hydrocarbons
(b) CO₂, NO₂, SO₂ and hydrocarbons
(c) NO, NO₂, O₃ and hydrocarbons
(d) N₂, O₂, O₃ and hydrocarbons
Show Answer & Explanation

Answer: (c) NO, NO₂, O₃ and hydrocarbons

Explanation:
1. Photochemical smog forms when sunlight acts on nitrogen oxides and unsaturated hydrocarbons.
2. The key species are NO, NO₂, O₃ and hydrocarbons, giving PAN and aldehydes.

Teacher's Note:
1. Primary pollutants are NO and hydrocarbons; secondary pollutants are O₃, PAN and aldehydes.

Question 7: The primary pollutant that leads to photochemical smog is:
(a) acrolein
(b) nitrogen oxides
(c) ozone
(d) sulphur dioxide
Show Answer & Explanation

Answer: (b) nitrogen oxides

Explanation:
1. Nitrogen oxides from vehicle exhaust and unburnt hydrocarbons are the primary pollutants.
2. Ozone and acrolein are secondary pollutants formed afterwards.

Teacher's Note:
1. A primary pollutant is released directly; a secondary one forms in the atmosphere.

Question 8: The condition for methemoglobinemia in drinking water is:
(a) more than 50 ppm nitrate
(b) more than 50 ppm chloride
(c) more than 50 ppm lead
(d) more than 100 ppm sulphate
Show Answer & Explanation

Answer: (a) more than 50 ppm nitrate

Explanation:
1. Excess nitrate (above 50 ppm) in drinking water causes methemoglobinemia, the blue baby syndrome.
2. Nitrate comes largely from fertilisers.

Teacher's Note:
1. Nitrate in water is converted to nitrite in the body and prevents haemoglobin from carrying oxygen.

Question 9: The pH of rain water is approximately:
(a) 7.5
(b) 6.5
(c) 5.6
(d) 7.0
Show Answer & Explanation

Answer: (c) 5.6

Explanation:
1. Rain water dissolves CO₂ to form carbonic acid.
2. This makes clean rain slightly acidic, pH about 5.6.

Teacher's Note:
1. Acid rain has a pH below 5.6.

Question 10: The reaction that is not involved in the ozone layer depletion mechanism in the stratosphere is:
(a) CH₄ + 2O₃ → 3CH₂=O + 3H₂O
(b) ClO·(g) + O(g) → Cl·(g) + O₂(g)
(c) HOCl(g) → ·OH(g) + Cl·(g) (hν)
(d) CF₂Cl₂(g) → Cl·(g) + ·CF₂Cl(g) (hν)
Show Answer & Explanation

Answer: (a) CH₄ + 2O₃ → 3CH₂=O + 3H₂O

Explanation:
1. The reactions of CFCs, Cl· and ClO· take place in the stratosphere and destroy ozone.
2. The reaction of methane with ozone belongs to the formation of photochemical smog in the troposphere.

Teacher's Note:
1. CFCs reach the stratosphere because they are very stable in the troposphere.

Question 11: The concentration of dissolved oxygen (DO) in cold water can go up to:
(a) 14 ppm
(b) 10 ppm
(c) 8 ppm
(d) 16 ppm
Show Answer & Explanation

Answer: (b) 10 ppm

Explanation:
1. Cold water can hold up to about 10 ppm of dissolved oxygen.
2. At room temperature normal water has a lower value.

Teacher's Note:
1. The lower the DO, the more polluted the water.

Question 12: A higher concentration of which gas in the air can cause stiffness of flower buds?
(a) SO₂
(b) CO
(c) CO₂
(d) NO₂
Show Answer & Explanation

Answer: (a) SO₂

Explanation:
1. SO₂ dissolves in moisture to form sulphurous and sulphuric acid.
2. The acid bleaches the pigments and makes the buds stiff, so they fall off.

Teacher's Note:
1. SO₂ is also the main cause of acid rain and of marble corrosion.

Question 13: The molecule that has minimum or no role in the formation of photochemical smog is:
(a) N₂
(b) CH₂=O
(c) NO
(d) O₃
Show Answer & Explanation

Answer: (a) N₂

Explanation:
1. NO, O₃ and formaldehyde are all involved in the smog reactions.
2. N₂ is very stable and does not react under ordinary conditions.

Teacher's Note:
1. N₂ reacts with O₂ only at very high temperatures such as in engines.

Question 14: The compound that is not a common component of photochemical smog is:
(a) CF₂Cl₂
(b) CH₃COOONO₂
(c) CH₂=CHCHO
(d) O₃
Show Answer & Explanation

Answer: (a) CF₂Cl₂

Explanation:
1. PAN, acrolein and ozone are components of photochemical smog.
2. CF₂Cl₂ (a freon) is a stratospheric pollutant related to ozone depletion.

Teacher's Note:
1. Smog is tropospheric; freons act in the stratosphere.

Question 15: The upper stratosphere, consisting of the ozone layer, protects us from the sun's radiation that falls in the wavelength region of:
(a) 600 to 750 nm
(b) 400 to 550 nm
(c) 0.8 to 1.5 nm
(d) 200 to 315 nm
Show Answer & Explanation

Answer: (d) 200 to 315 nm

Explanation:
1. Ozone absorbs harmful ultraviolet radiation.
2. The UV-B and UV-C range of about 200 to 315 nm is absorbed.

Teacher's Note:
1. Visible light (400 to 750 nm) passes through the ozone layer.

Question 16: The concentrations of fluoride, lead, nitrate and iron in a water sample from an underground lake were 1000 ppb, 40 ppb, 100 ppm and 0.2 ppm respectively. This water is unsuitable for drinking due to the high concentration of:
(a) lead
(b) nitrate
(c) iron
(d) fluoride
Show Answer & Explanation

Answer: (b) nitrate

Explanation:
1. Limits: lead about 50 ppb, nitrate 50 ppm, iron 0.2 ppm and fluoride about 1 ppm (1000 ppb).
2. Only nitrate (100 ppm) exceeds its limit.

Teacher's Note:
1. Convert units (1 ppm = 1000 ppb) before comparing.

Question 17: Assertion: Nitrogen and oxygen are the main components of the atmosphere but they do not react to form oxides of nitrogen. Reason: The reaction between nitrogen and oxygen requires high temperature. Choose the correct option.
(a) Both are correct and the reason explains the assertion
(b) Both are correct but the reason does not explain the assertion
(c) The assertion is incorrect but the reason is correct
(d) Both are incorrect
Show Answer & Explanation

Answer: (a) Both are correct and the reason explains the assertion

Explanation:
1. The strong N≡N bond makes nitrogen inert under ordinary conditions.
2. Only at very high temperatures (about 2000 K) does N₂ react with O₂ to give NO, so the reason explains the assertion.

Teacher's Note:
1. Nitrogen oxides form in engines and lightning, where the temperature is very high.

Question 18: What is DDT among the following?
(a) Green house gas
(b) A fertiliser
(c) Biodegradable pollutant
(d) Non-biodegradable pollutant
Show Answer & Explanation

Answer: (d) Non-biodegradable pollutant

Explanation:
1. DDT is a chlorinated organic insecticide.
2. It is not broken down by microorganisms and accumulates in food chains, so it is a non-biodegradable pollutant.

Teacher's Note:
1. Biomagnification of DDT affects birds at the top of the food chain.

Question 19: Identify the incorrect statement from the following:
(a) Oxides of nitrogen in the atmosphere can cause the depletion of the ozone layer
(b) Ozone absorbs the intense ultraviolet radiations of the sun
(c) Depletion of the ozone layer is because of its chemical reactions with chlorofluoroalkanes
(d) Ozone absorbs infrared radiations
Show Answer & Explanation

Answer: (d) Ozone absorbs infrared radiations

Explanation:
1. NO reacts with ozone, and CFCs deplete ozone through Cl radicals, so (a) and (c) are correct.
2. Ozone absorbs ultraviolet, not infrared, radiation, so (d) is incorrect.

Teacher's Note:
1. The ozone layer is permeable to infrared and visible light but blocks harmful UV.

Question 20: When rain is accompanied by a thunderstorm, the collected rain water will have a pH value:
(a) slightly lower than that of rain water without thunderstorm
(b) slightly higher than that when the thunderstorm is not there
(c) uninfluenced by the occurrence of thunderstorm
(d) which depends on the amount of dust in the air
Show Answer & Explanation

Answer: (a) slightly lower than that of rain water without thunderstorm

Explanation:
1. Lightning combines N₂ and O₂ to give NO, which forms NO₂ and finally HNO₃.
2. The extra nitric acid lowers the pH.

Teacher's Note:
1. Thunderstorms add nitric acid to the rain, making it more acidic.

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