General Science Questions (MCQs) for Competitive Examinations

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Antiseptics are applied to the living tissues such as wounds, cuts, ulcers and diseased skin surfaces. Examples of antiseptics are furacine, soframicine, etc

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Sublimation describes a phase transition where a substance changes from a solid directly to a gas, bypassing the liquid state. This physical transformation is distinct from chemical changes like oxidation or reduction. Sublimation happens under certain combinations of pressure and temperature. Examples include dry ice (solid CO2), which sublimates at room temperature, and solid water, or ice, which sublimates under low pressure conditions.

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Radon, a radioactive noble gas with atomic number 86, is used in radiotherapy. Created by disintegration of radium, its one of the heaviest gases and a health hazard. Radon gas, chemically inert yet radioactive, can accumulate in buildings and drinking water causing lung cancer. Furthermore, radon is noted for brilliant phosphorescence when cooled below its freezing point. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Groundwater often has a higher 222Rn concentration than surface water due to less exposure to atmosphere.

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Greenhouse gases that occur both naturally and from human activities include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3). These gases contribute to atmospheric warming when they absorb infrared radiation emitted by the solar-warmed Earth and transfer their extra energy to the surrounding atmospheric gases.

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Plants obtain nitrogen through their roots. In the soil, nitrifying bacteria change ammonia into nitrite (NO2 –) and then into nitrate (NO3 –), this process is known as nitrification. Furthermore, plants also absorb nitrogen in an organic form. Several organic compounds (compounds containing carbon) constitute the organic fraction of nitrogen in the soil. The organic matter in the soil exists as decomposing plant and animal residues, relatively stable decomposition-resistant compounds, and humus. The abundance of various forms of nitrogen can be altered by plant roots through the change in pH and secretion of organic compounds or oxygen.

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Animals, such as mammals and birds, that maintain a constant body temperature regardless of the temperature of the surroundings are called warm blooded. These include birds and mammals. Whales are aquatic mammals hence, being mammal, they are warm blooded. The have a thick layer of fats called blubber underneath their skin to maintain temperature even in cold water of oceans.

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A layer of body fat acts as an insulator and traps heat. The subcutis is the deepest layer of skin. The subcutis, consisting of a network of collagen and fat cells, helps conserve the body’s heat and protects the body from injury by acting as a “shock absorber.

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The masseter is located in the jaw and is one of the muscles of mastication or chewing. ? The bite strength of an average man is between 117 to 265 pounds. ? This ability to exert a force on an external object is an example of absolute strength.

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The word “protoplasm” comes from the Greek protos for first, and plasma for thing formed, and was originally used in religious contexts. It was first used for living cells by J. E. Purkinje, a Czech anatomist and physiologist, in 1839. He used protoplasm for the fluid substance of a cell.

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Pulse, in botany, is a common name for members of the Fabaceae (Leguminosae), a large plant family. Pulses, high in protein, are used as food for humans and other animals. Besides, they play a key role in crop rotation due to their ability to fix nitrogen.