General Science Questions (MCQs) for Competitive Examinations

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All metal carbonates and hydrogen carbonates react with acids to give a corresponding salt, carbon dioxide and water. Limestone, chalk and marble are different forms of calcium carbonate.

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Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2. 1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.

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Radioactive materials are first encased in resin or concrete and sealed in steel drums. The drums are then packed into concrete casks and placed in concrete trenches up to 18 metres deep.

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The petiole is the stalk-like structure which connects the leaf blade to the stem. The petiole has tiny tubes, that connect the veins on the leaf blade to the stem. Few of these enable water transport to the leaf while the other carry food away from the leaf to other parts of the plant.

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The brain’s limbic system controls emotional expression through the hypothalamus, which has control over the body’s emotional responses systems. The hypothalamus is responsible for regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, etc. It also regulates pulse, blood pressure, breathing, and arousal in response to emotional circumstances.

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Milk is a poor source of ascorbic acid (Vitamin C). It contains about 1 mg ascorbate per 100 g. Even the little Vitamin C is usually destroyed when the milk is heat treated. Milk as a complete food contains most of the esential nutrients except are vitamin C and iron.

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Calyptrogen is a layer of rapidly dividing cells at the tip of a plant root, from which the root cap is formed. It occurs in grasses and many other plants. The root cap is formed by several layers of cells that envelop the root tip externally. This covering of cells, of which the outermost ones are dead, envelops and protects the growing tip of root.

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Newton’s Law of Cooling states that the rate of temperature of the body is proportional to the difference between the temperature of the body and that of the surrounding medium. When a body cools by radiation, then rate of cooling depends on: Nature of the radiating surface, that is, emissivity; Area of the radiating surface; Mass of the radiating surface; Specific heat of the radiating body; Temperature of radiating body and Temperature of the surrounding.

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Vitamin C is quite unstable when cooked or stored improperly. It is very liable and easily destroyed during cooking as well as storage. It is a water-soluble and temperature-sensitive vitamin, so is easily degraded during cooking, and elevated temperatures and long cooking times have been found to cause particularly severe losses of vitamin C.

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Female gametes are also called eggs or ova. They are created during the cellular reproduction process known as meiosis. The resulting gamete cell is a haploid cell. When the two haploid cells, the egg and sperm, fuse together during fertilization, the result is a diploid cell called a zygote.