Chemistry MCQs

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Bananas contain potassium-40, a radioactive isotope of potassium, which makes them slightly radioactive. The radiation is very minor and not dangerous at all to humans, but it is enough to trigger sensitive radiation sensors. The potassium provides bananas some of their nutritional benefits as well.

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Mercury is a chemical element with the symbol Hg and atomic number 80. The element is also known as quicksilver for its mobility. Mercury is one of the oldest and deadliest poisons, a highly toxic metal mined from a brilliant red ore.

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A catalyst is a substance that increases the rate of a chemical reaction without undergoing any permanent change itself. At the end of the reaction, a catalyst retains its original quantity and chemical composition. This property allows it to be used repeatedly in reactions. For example, enzymes, which are biological catalysts, remain unchanged after facilitating biochemical reactions.

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Cassiterite is a mineral that is a significant ore of tin. It is also known as tin oxide. Although rare, its key characteristic is its high specific gravity that makes it easy to separate it from other materials. Tin, which is extracted from Cassiterite, is commonly used in making alloys, punches, and cutting tools.

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The first synthetic plastic was actually celluloid, invented by Alexander Parkes in 1855. Initially, celluloid was primarily used in photographic films. However, it had limitations, not suitable for making containers or electrical insulation. The first genuine plastic, Bakelite, was invented by Leo Baekeland in 1909 and extensively used in various applications, including safely handled autos. World War I significantly contributed to the development of polystyrene and polyvinyl chloride, widely used in plumbing and electrical insulation. Later, in the 1930s, nylon was invented, and by 1950, plastic materials gained immense popularity.

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Bleaching powder is made by passing Cl2 into slaked lime. Though bleaching powder is often written as Ca(OCl)₂ , it is really a mixture and not a compound.

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Of the alkaline earth metals calcium and magnesium rank fifth and sixth in abundance respectively in the earth’s crust. Strontium and barium have much lower abundances. Beryllium is rare and radium is the rarest of all comprising only 10^–10 per cent of igneous rocks.

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5-8% solution of acetic acid in water is called vinegar and is used widely as a preservative in pickles

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Gypsum is a mineral composed of calcium sulfate dihydrate. It’s a soft mineral and colorless to white in color. It is commonly added to saline soils to reduce salinity and also used in wallboard (drywall) and plaster of paris.

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Magnetite > Haemetite > Limonite > Siderite . Magnetite has 72.4% iron content. Haematite has 70% iron content. Limonite has 55% iron content. Siderite has 48.2% iron content.