General Science/Everyday Science MCQs
Topic Notes: General Science/Everyday Science
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
361
How does Biological Oxygen Demand (BOD) change with more organic matter in water?
Answer:
BOD increases
Organic matter requires oxygen for microbial decomposition. More organic waste means microbes consume more dissolved oxygen, increasing BOD. High BOD indicates pollution and reduced oxygen available for aquatic life.
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362
The greenhouse effect is caused by:
Answer:
Infrared radiation
Greenhouse gases trap outgoing infrared radiation, warming Earth’s surface. Without this effect, Earth would be much colder. Human activities have enhanced the greenhouse effect, driving climate change.
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363
DDT is classified as a:
Answer:
Non-degradable pollutant
DDT (dichlorodiphenyltrichloroethane) is a persistent organic pollutant. It accumulates in food chains and magnifies in higher trophic levels. Its persistence led to widespread bans despite its initial success as an insecticide.
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364
The Taj Mahal is said to suffer from "Marble Cancer." What does this mean?
Answer:
Acid rain corroding marble
Acid rain, caused by SO₂ and NOx emissions, reacts with calcium carbonate in marble to form gypsum. This weakens and corrodes the Taj Mahal’s structure, a process called "marble cancer." Soot also contributes to discoloration, but acid rain is the main factor.
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365
Which gas dissolves in blood hemoglobin more readily than oxygen when inhaled?
Answer:
Carbon monoxide
Carbon monoxide binds hemoglobin about 200 times more strongly than oxygen, forming carboxyhemoglobin. This reduces oxygen delivery to tissues and can cause poisoning or death. Other gases do not bind with the same affinity.
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366
During a temperature inversion:
Answer:
Temperature increases with altitude
Normally, air cools with altitude. In an inversion, a warmer air layer traps cooler air near the ground. This prevents vertical mixing and leads to pollution build-up and smog events.
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367
Which of the following is a secondary air pollutant?
Answer:
secondary air pollutant?
Primary pollutants are emitted directly, while secondary pollutants form by chemical reactions in the atmosphere. Ozone is produced by sunlight acting on nitrogen oxides and hydrocarbons. It is harmful at ground level though beneficial in the stratosphere.
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368
Which of the following is an air pollutant?
Answer:
Carbon monoxide
Carbon monoxide (CO) is a toxic gas produced by incomplete combustion of fuels. It binds to hemoglobin more strongly than oxygen, reducing oxygen transport in blood. Nitrogen, oxygen, and elemental carbon are not pollutants under normal atmospheric conditions.
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369
The entry of toxic chemicals into food chains, with increasing concentration at higher trophic levels, is called:
Answer:
Biomagnification
Biomagnification occurs when pollutants like mercury or pesticides accumulate at progressively higher levels in the food chain. Top predators face the highest risks due to concentration. This disrupts ecosystems and endangers health.
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Perfect 👍 Let’s keep the sequence going — we’ll continue from **Q139** with the same MCQ style (statement, shuffled options, correct answer, and 3–5 sentence explanation).
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370
In a national park, protection is given to:
Answer:
national park, protection is given to:
National parks conserve biodiversity by protecting habitats, ecosystems, and species together. They safeguard ecological processes as well as individual organisms. This holistic approach ensures long-term ecological balance.
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