Chemistry MCQs

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Fractional Distillation is based on the fact that the different components of oil have different boiling points. In this process, oil is heated in a furnace to 400 degree Celsius(752 F) and it vapourises. The vapours are introduced into a tall fractionating column.

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The sulfate or sulphate ion is a polyatomic anion with the empirical formula SO₄²⁻. Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life.

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In oxidation, iron reacts with oxygen it forms a chemical called rust because it has been oxidized (the iron has lost some electrons) and the oxygen has been reduced (the oxygen has gained some electrons).

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A pearl is largely made of calcium carbonate, CaCO3, and that compound occurs mostly as platelets having the structure of a naturally-occurring mineral called aragonite.

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Urea is also known as carbamide. It is an organic compound with chemical formula CO (NH₂)₂.

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Fat has more than twice as many calories per gram as carbohydrates and proteins. A gram of fat has about 9 calories, while a gram of carbohydrate or protein has about 4 calories.

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Thyroxine, the most abundant thyroid hormone, contains four iodine atoms and is nicknamed T4, while triiodothyronine, the most active form, has three and is referred to as T3. CAPTION: The thyroid synthesizes thyroid hormone from tyrosine and iodide.

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Oil of cloves, also known as Clove oil, is an essential oil obtained from the clove plant. It is a natural analgesic and antiseptic used primarily in dentistry for its main ingredient eugenol. The oil produced by cloves can be used in many things from flavouring medicine to remedies for bronchitis, common cold, a cough, fever, sore throat and tending to infections.

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Garlic is known to cause bad breath and body odor, described as a pungent “garlicky” smell to sweat. This is caused by allyl methyl sulfide (AMS). The sulfur compound allicin, produced by crushing or chewing fresh garlic, produces other sulfur compounds: ajoene, allyl polysulfides, and vinyldithiins.

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Oxygen is by far the most abundant element in the earth’s crust. Scientists estimate oxygen comprises nearly half of the mass of the crust. It also accounts for 21 percent of Earth’s atmosphere. Almost 97% of Earth’s crust is made up of just eight elements.
Elements occurred in Earth crust in form of minerals or in compound form. The mineral composition of our planets crust is highly non-uniform. Earth is missing a great deal of the volatile elements such as hydrogen, helium, neon, and nitrogen, as well as carbon which has been lost as volatile hydrocarbons. The remaining elemental composition is roughly typical of the “rocky” inner planets.