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
281
Automobile air pollution can be controlled by fitting a:
Answer:
Catalytic converter
Catalytic converters convert CO and hydrocarbons to CO₂ and H₂O and reduce NOx. ESPs and scrubbers are used in stationary industrial stacks, not cars. Three-way catalysts are standard in modern petrol vehicles.
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282
Smog is:
Answer:
Combination of smoke and fog
Classic smog results from particulate-laden smoke mixing with fog; modern **photochemical smog** involves NOx/VOCs and sunlight, forming ozone and aerosols. It reduces visibility and harms health. It is not colorless nor purely natural.
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283
A major source of **thermal pollution** of water bodies is:
Answer:
Thermal power plants
Power plants discharge heated cooling water, elevating the temperature of receiving waters. Warmer water holds less dissolved oxygen and can stress aquatic life. Cooling towers and closed-loop systems mitigate this.
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284
A **nonpoint** source of water pollution among the following is:
Answer:
Urban and suburban land
Runoff from streets, lawns, and construction sites is diffuse and lacks a single discharge pipe. Factories and treatment plants are point sources. Nonpoint sources are major contributors to nutrient and sediment loads.
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285
Excess iron in water commonly causes:
Answer:
Colour (staining)
Dissolved iron oxidizes and precipitates, causing reddish-brown staining and discoloration; metallic taste may occur but iron is **not** a primary cause of hardness (Ca²⁺/Mg²⁺ are). Water treatment may include aeration and filtration. Given the options, color/staining is the most characteristic effect.
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286
Deforestation can:
Answer:
Introduce silt into rivers
Removing vegetation increases erosion, carrying sediments into rivers and reservoirs. This causes siltation, reducing storage and harming habitats. Deforestation often reduces local rainfall and soil fertility over time.
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287
Which of the following is **surface water**?
Answer:
Streams
Streams (and rivers, lakes) are classic surface water bodies. Deep wells tap groundwater. Springs are groundwater discharges at the surface but are typically classified by their groundwater origin; the clearest choice here is streams.
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288
Physical pollution of water is indicated by:
Answer:
y:
Turbidity measures suspended particles that reduce clarity—this is a physical (not chemical) characteristic. DO and pH are chemical indicators. High turbidity can harbor pathogens and reduce light penetration.
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289
Which industry commonly generates **colored** wastewater?
Answer:
Textile industry
Dyeing and finishing processes discharge intensely colored effluents containing dyes and auxiliaries. Treatment often requires coagulation, adsorption, or advanced oxidation. Color removal is a major compliance challenge.
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290
BOD stands for:
Answer:
Biochemical Oxygen Demand
BOD measures the dissolved oxygen needed by microbes to decompose organic matter in water. High BOD indicates pollution and low oxygen available for aquatic life. It is a key indicator of wastewater quality.
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