Which of the following is known as a quiet killer?
Correct answer: C. CO
- A. CO2
- B. NO2
- C. CO
- D. SO2
Explanation
Carbon monoxide (CO) is known as the "silent" or "quiet killer" because it is a colorless, odorless gas that is highly toxic to humans and animals. It is produced by incomplete combustion of carbon-containing fuels such as wood, gasoline, natural gas, and coal. CO binds to hemoglobin in the blood much more readily than oxygen does, forming carboxyhemoglobin. This reduces the blood's ability to carry oxygen, leading to tissue hypoxia (oxygen deficiency) and, in severe cases, death.
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Atmospheric pollution includes smog, acid rain, greenhouse gases, ozone depletion and the effects of carbon monoxide, sulfur oxides, nitrogen oxides and particulate matter. Water pollution covers sewage, industrial waste, eutrophication and treatment stages, while green chemistry focuses on reducing hazardous substances, waste and energy use through safer, more efficient processes.
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