Chemistry MCQs

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Detergents yields froth with both hard and soft water while soaps yield froth only with soft water not hard water.

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Calcium carbonate equivalents.

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Sludge refers to the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. It can be used to produce biogas through a process called anaerobic digestion or fermentation.

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Ernest Rutherford directed beams of alpha particles (which are the nuclei of helium atoms and hence positively charged) at thin gold foil to test this model and noted how the alpha particles scattered from the foil. He realised that the positively charged alpha particles were being repelled and deflected by a tiny concentration of positive charge in the atom. As a result of this experiment, the plum pudding model was replaced by the nuclear model of the atom.

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Nuclear reactors function by delaying (moderating) the fastest neutrons or increasing the proportion of fissile atoms. To slow these neutrons, called slow neutrons, a moderator such as graphite is needed. Commonly-used moderators include regular (light) water (in 74.8% of the world’s reactors), solid graphite (20% of reactors) and heavy water (5% of reactors.

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Flames are formed when a fuel gas, like acetylene, reacts with a support gas such as oxygen. This reaction creates a lot of heat and light, which we see as a flame. An oxygen acetylene flame can create temperatures over 3200°C. Pure oxygen, instead of air (20% oxygen/80% nitrogen), is used to increase the flame temperature to allow localized melting of the work piece material (e.g. steel) in a room environment. A common propane/air flame burns at about 3,630 degree F (2,000 degree C), a propane/ oxygen flame burns at about 4,530 degree F (2,500 degree C), and an acetylene/oxygen flame burns at about 6,330 degree F (3,500 degree C).

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In chemistry, a homologous series is a series of compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group. C6H14 stands for Hexane which is an alkane with six carbon atoms. In the alkane homologous series, each member differs from the previous one by a CH2 group (or 14 atomic mass units). The CH2 group is called Methylene Group. So the higher homologue of Hexane is Heptane (C7H16).

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Terylene is a co-polymer of ethylene glycol and terephthalic acid. Also known as Dacron, it is prepared by the condensation polymerization of ethylene glycerol and terephthalic acid with elimination of water. The reaction is carried out at about 420-460 K in the presence of a catalyst consisting of a mixture of zinc acetate and antimony trioxide.

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In chemistry, an organic compound is generally any chemical compound that contains carbon. Organic compounds contain carbon bonds in which at least one carbon atom is covalently linked to an atom of another type (usually hydrogen, oxygen or nitrogen). Most polymers are organic compounds.

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In the late 1920s and the early 1930s, chemists at the DuPont Company first produced nylon by combining chemicals they extracted from coal, water, air, petroleum, natural gas, and agricultural by-products. Nylon was the first fully synthetic fibre because it was a man-made fibre. Strong, elastic and light, it was actually stronger than a steel wire.