Selected MCQ

Current Question
Which gas contributes to ozone depletion?
  • A. CO₂
  • B. CFC
  • C. N₂
  • D. O₂
Correct Answer: B
Explanation:
CFCs release chlorine radicals.
Related Question 1
Which gas is ozone?
  • A. O₂
  • B. O₃
  • C. CO₂
  • D. N₂
Correct Answer: B
Explanation:
Ozone is triatomic oxygen.
Related Question 2
Which gas contributes most to greenhouse effect after water vapor?
  • A. Methane
  • B. CO₂
  • C. Ozone
  • D. Nitrogen
Correct Answer: B
Explanation:
CO₂ is major anthropogenic greenhouse gas.
Related Question 3
The ozone hole over Antarctica is strongly linked to catalytic destruction by radicals derived from:
  • A. Sulfur dioxide
  • B. Chlorofluorocarbons
  • C. Nitrogen gas
  • D. Carbonate aerosols
Correct Answer: B
Explanation:
Photolysis of CFC-derived halogens generates radicals that destroy stratospheric ozone.
Related Question 4
Crossing over during meiosis contributes directly to:
  • A. DNA replication arrest
  • B. Genetic recombination
  • C. Chromosome number doubling
  • D. Cytokinesis prevention
Correct Answer: B
Explanation:
Exchange between homologous chromatids creates new allele combinations.