UET Lahore ECAT Chemistry: Environmental Chemistry MCQs

UET Lahore ECAT Chemistry: Environmental Chemistry MCQs — sample questions

1. Question 1

   Q1. The pH of a solution is 4. The concentration of H+ ions is

   • A) 10^-4 M
   • B) 10^-10 M
   • C) 10^-7 M
   • D) 10^-2 M

   Answer: 10^-4 M

   Explanation: pH = -log[H+], so [H+] = 10^-pH = 10^-4 M

2. Question 2

   Q2. The most toxic form of mercury is

   • A) Elemental mercury
   • B) Methylmercury
   • C) Mercuric chloride
   • D) Mercurous chloride

   Answer: Methylmercury

   Explanation: Methylmercury is a potent neurotoxin that accumulates in the food chain

3. Question 3

   Q3. The main cause of acid rain is

   • A) CO2 emissions
   • B) SO2 and NOx emissions
   • C) CFC emissions
   • D) CH4 emissions

   Answer: SO2 and NOx emissions

   Explanation: SO2 and NOx react with water and oxygen to form H2SO4 and HNO3, causing acid rain

4. Question 4

   Q4. The BOD of a water sample is a measure of

   • A) Oxygen consumed by microorganisms
   • B) Oxygen produced by phytoplankton
   • C) pH of the water
   • D) Turbidity of the water

   Answer: Oxygen consumed by microorganisms

   Explanation: BOD = Biochemical Oxygen Demand, measures oxygen consumed by microorganisms

5. Question 5

   Q5. The ozone layer is depleted by

   • A) CO2
   • B) CH4
   • C) CFCs
   • D) N2O

   Answer: CFCs

   Explanation: CFCs release Cl atoms, which catalytically destroy O3 molecules

6. Question 6

   Q6. The main sink for CO2 is

   • A) Oceans
   • B) Atmosphere
   • C) Biosphere
   • D) Lithosphere

   Answer: Oceans

   Explanation: Oceans absorb CO2 through chemical reactions and biological processes

7. Question 7

   Q7. The concentration of a pollutant is often expressed in

   • A) ppm
   • B) ppb
   • C) ppt
   • D) All of the above

   Answer: All of the above

   Explanation: ppm, ppb, and ppt are units used to express concentrations of pollutants

8. Question 8

   Q8. The greenhouse effect is caused by

   • A) CO2
   • B) H2O
   • C) Both CO2 and H2O
   • D) O3

   Answer: Both CO2 and H2O

   Explanation: CO2 and H2O are both greenhouse gases that trap heat

9. Question 9

   Q9. The pE of a solution is a measure of

   • A) pH
   • B) Redox potential
   • C) Oxygen demand
   • D) Turbidity

   Answer: Redox potential

   Explanation: pE = -log[e-], measures the tendency of a solution to donate or accept electrons

10. Question 10

    Q10. The most common method of wastewater treatment is

    • A) Physical treatment
    • B) Chemical treatment
    • C) Biological treatment
    • D) Advanced treatment

    Answer: Biological treatment

    Explanation: Biological treatment uses microorganisms to break down organic matter

11. Question 11

    Q11. The COD of a water sample is

    • A) Always less than BOD
    • B) Always greater than BOD
    • C) Equal to BOD
    • D) Unrelated to BOD

    Answer: Always greater than BOD

    Explanation: COD measures oxygen required to oxidize all organic matter, while BOD measures oxygen consumed by microorganisms

12. Question 12

    Q12. The photochemical smog is formed by

    • A) Reaction of NOx and VOCs in presence of sunlight
    • B) Reaction of SO2 and CO in presence of sunlight
    • C) Reaction of CO2 and H2O in presence of sunlight
    • D) Reaction of N2 and O2 in presence of sunlight

    Answer: Reaction of NOx and VOCs in presence of sunlight

    Explanation: NOx and VOCs react in presence of sunlight to form ground-level O3 and other pollutants

13. Question 13

    Q13. The major source of particulate matter in the atmosphere is

    • A) Fossil fuel combustion
    • B) Industrial processes
    • C) Agricultural activities
    • D) Natural sources

    Answer: Fossil fuel combustion

    Explanation: Fossil fuel combustion releases particulate matter, including soot and aerosols

14. Question 14

    Q14. The environmental fate of a pollutant is determined by its

    • A) Chemical structure
    • B) Physical properties
    • C) Both chemical structure and physical properties
    • D) Biological properties

    Answer: Both chemical structure and physical properties

    Explanation: Both chemical structure and physical properties influence the fate and transport of pollutants

15. Question 15

    Q15. The water quality parameter that is a measure of the amount of oxygen required to oxidize organic matter is

    • A) BOD
    • B) COD
    • C) TOC
    • D) All of the above

    Answer: All of the above

    Explanation: BOD, COD, and TOC are all measures of oxygen demand or organic matter content

16. Question 16

    Q16. The major sink for methane is

    • A) Atmosphere
    • B) Oceans
    • C) Soils
    • D) Troposphere

    Answer: Soils

    Explanation: Methane is oxidized by microorganisms in soils, reducing its atmospheric concentration

17. Question 17

    Q17. The process by which pollutants are transferred from one trophic level to the next is

    • A) Biomagnification
    • B) Bioaccumulation
    • C) Biodegradation
    • D) Bioconcentration

    Answer: Biomagnification

    Explanation: Biomagnification occurs when pollutants are transferred and concentrated through the food chain

18. Question 18

    Q18. The primary effect of eutrophication is

    • A) Increased biodiversity
    • B) Decreased water clarity
    • C) Increased oxygen levels
    • D) Algal blooms

    Answer: Algal blooms

    Explanation: Eutrophication leads to excessive algal growth, causing algal blooms

19. Question 19

    Q19. The major environmental impact of particulate matter is

    • A) Climate change
    • B) Air pollution
    • C) Water pollution
    • D) Soil pollution

    Answer: Air pollution

    Explanation: Particulate matter contributes to air pollution, negatively impacting human health

20. Question 20

    Q20. The process of removing pollutants from contaminated soil is

    • A) Bioremediation
    • B) Phytoremediation
    • C) Both A and B
    • D) None of the above

    Answer: Both A and B

    Explanation: Bioremediation and phytoremediation are both techniques used to clean up contaminated soil