General Science Questions (MCQs) for Competitive Examinations

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Magnetite, followed by Hematite – Limonite – Siderite

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As per the Mohs scale of mineral hardness, the soft metals are: Lead, gold, silver, tin, zinc, aluminium, thorium, copper, brass and bronze. Diamond is one of the hardest known metals on earth.

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Because of the screening effect, the net positive charge experienced by the electron from the nucleus is lowered and is known as effective nuclear charge. Effective nuclear charge experienced by the orbital decreases with increase of azimuthal quantum number(l).

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Edible seaweed products have been consumed in many Asian countries. Edible seaweeds accumulate iodine from seawater and are therefore a good dietary source of iodine. Adequate consumption of seaweed can eliminate iodine deficiency disorders, but excessive iodine intake is not good for health. The recommended dietary reference intake of 0.15 mg/d and 0.14 mg/d for iodine has been established in the United States and Taiwan, respectively. Seaweed is an excellent source of iodine. However, the amount it contains depends on the species. Kombu kelp offers the highest amount of iodine, with some varieties containing nearly 2,000% of the daily value in one gram. Seaweed is a source of iodine, necessary for thyroid function and to prevent goitre. However, an excess of iodine is suspected in the heightened cancer risk in Japanese who consume a lot of the plant, and even bigger risks in post-menopausal women.

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Keratin is a family of fibrous structural proteins that is the key structural component of hair and nails. It is also the key structural material making up the outer layer of human skin. Besides, it provides the necessary strength and toughness for masticatory organs, such as the tongue.

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During hibernation in winter, toads or frogs spend the time tucked away deep in the soil, in the mud underwater or hidden amidst foliage or rotting plants. Outside of times of hibernation, they usually take in oxygen via the air, employing their lungs. However, during hibernation, they receive their necessary oxygen through their permeable skin. This is referred to as cutaneous gas exchange.

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Monocost and dicots differ in the location of stomata and shape of guard cells. In monocots stomata are Dumb-bell shaped in dicots they are bean-shaped.

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Motor skills are needed to control the movements of the different muscles in the human body. The frontal lobe plays a large role in voluntary movement. It houses the primary motor cortex which regulates activities like walking. The frontal lobes are also involved in problem solving, spontaneity, memory, language, initiation, judgement, impulse control, etc.

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Insects and birds have the simplest surface waxes that serve to water proof feathers. The interlocking feather barbs and a special waxy coating create a shield that water runs off of. Besides, while a few components present in surface lipids can prevent growth of pathogens, the total surface with waxed layer certainly functions to prevent microbial entry into the organism.

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Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by products. It is an anaerobic process since Yeasts perform this conversion in the absence of oxygen.