Chemistry MCQs

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The red litmus turns blue when the solution is basic in nature. The aqueous magnesium oxide is basic in nature and when the red litmus paper was dipped into the solution then it became blue.

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Galvanization is a process in which coat of zinc is applied to the thicker base metal surface which are prone to corrosion such as iron. The most common method is hot-dip galvanizing, in which the parts are submerged in a bath of molten zinc.

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Aqueous solution of Washing Soda or Sodium Carbonate Decahydrate (Na2CO3.10H2O) is Alkaline in nature. Na2CO3 reacts with water to give NaOH and CO2.

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Calcium carbide is also used in some countries for artificially ripening fruit. When calcium carbide comes in contact with moisture, it produces acetylene gas, which is quite similar in its effects to the natural ripening agent, ethylene. Acetylene acts like ethylene and accelerates the ripening process.

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In 1778, Antoine Lavoisier, considered “The father of modern chemistry”, recognized and named oxygen, and recognized its importance and role in combustion. Antoine Lavoisier discovered the relationship between oxygen and metal that leads to rust. He also proved the role of oxygen in respiration and discovered the chemical composition of water and air. Henry Cavendish discovered hydrogen in 1766 as a colorless, odorless gas that burns and can form an explosive mixture with air.

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The atom is the smallest unit of matter that is composed of three sub-atomic particles: the proton, the neutron, and the electron. Protons and neutrons make up the nucleus of the atom, a dense and positively charged core, whereas the negatively charged electrons can be found around the nucleus in an electron cloud. An atom consists of a positively charged nucleus surrounded by one or more negatively charged particles called electrons. The number of protons found in the nucleus equals the number of electrons that surround it, giving the atom a neutral charge (neutrons have zero charges). Most of an atom’s mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. Although the nucleus is heavy, it is small compared with the overall size of an atom.

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6PPD is the chemical which is present in the car tires and is responsible for killing fishes. It is the toxic substance which has been killing a large number of coho salmon. Nearly all tires world wide contain 6PPD and shed the toxic 6PPD-quinone which acts as a poison for the fishes.

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Ernest Rutherford and his fellows Geiger and Marsden proved between 1911 and 1913 the existence of the atomic nucleus. This scattering experiment led to the development of the Rutherford model of the atom based on D-scattering particle experimment and eventually to the Bohr model.

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Valency refers to the ability of an atom or a group of chemically bonded atoms to form chemical bonds with other atoms or groups of atoms. The valency of an element is determined by the number of outer shell (valence) electrons. A carbon atom has four electrons in its outermost valence shell. So, its valency is 4.

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Iodine is well known to sublime (change from solid to gas without under going the liquid phase when heated. However potassium chloride has a melting point much higher than that of iodine. Therefore, a mixture of iodine and potassium chloride can be separated by using a sublimation apparatus, with solid iodine collected on condensation of its vapour on a cold surface.