Chemistry MCQs

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Natural rubber becomes soft at high temperature (>335 K) and brittle at low temperatures (<283 k) and shows high water absorption capacity. It is soluble in non-polar solvents and is non-resistant to attack by oxidising agents. To improve upon these physical properties, a process of vulcanisation is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 K. On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened.
 In the manufacture of tyre rubber, 5% of sulphur is used as a crosslinking agent

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Hydrogen (H2) gas is utilized in the manufacture of Vanaspati ghee from vegetable oils. The process involves hydrogenation, a chemical reaction between molecular hydrogen (H2) and another compound or element. Hydrogenation of vegetable oils helps to convert them into a semisolid form that resembles ghee, often used as a cheaper alternative to butter or ghee in cooking.

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fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At)

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Brominated Vegetable Oil is an additive, which is used in artificial citrus flavoured aerated drinks to give it the cloudy look, so that consumers are fooled into believing that it is the real thing. India banned BVO in 1988. It is used in some countries.

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Pure ozone is a pale blue gas, dark blue liquid and violet-black solid. Ozone has a characteristic smell and in small concentrations it is harmless. However, if the concentration rises above about 100 parts per million, breathing becomes uncomfortable resulting in headache and nausea.

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Solder is an alloy of lead and tin (Pb and Sn). It has a low melting point and is used for welding electrical wires together.

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Corundum is an ore of Aluminium. It is a crystalline form of aluminium oxide. Kieserite is an ore of Magnesium and Pitch blende is an ore of Uranium.

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The probability of finding an electron at a point within an atom is proportional to the square of the orbital wave function i.e., ψ|² at that point. |ψ|² is known as probability density and is always positive.

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The radioactive decay of uranium-238 to thorium-234, with the emission of a helium nucleus, is a well-known example of alpha decay.

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Decomposition of calcium carbonate to calcium oxide and carbon dioxide is an endothermic reaction. Respiration and Burning of Natural gas are examples of exothermic reactions.