Chemistry MCQs

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Although there are other substances that will lighten hair, hydrogen peroxide is still very common in hair dye preparations. The hydrogen peroxide in the preparation acts as a bleach and strips the hair shaft of its colour; the amount of hydrogen peroxide you use on your hair will determine how “blond” you go.

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An emulsion is a mixture of two or more liquids that are normally immiscible. Emulsions are part of a more general class of two-phase systems of matter called colloids.

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Aspirin or acetylsalicylic acid is a pharmaceutical drug used to reduce pain or inflammation. It is classified as a non-steroidal anti-inflammatory drug (NSAID).

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Shellac is a resinous product obtained from the secretion of the female “lac bug” on trees, mostly in the forests of India and Thailand. The dry flake processed shellac is dissolved in ethanol to obtain liquid shellac, which is used as a brush-on colorant, food glaze, and wood finish.

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German Silver is an alloy of copper, zinc and nickel, sometimes also containing lead and tin. It was originally named for its silver-white colour, but the term ‘silver’ is now prohibited for alloys not containing that metal. German silver is extensively used because of its hardness and resistance to corrosion.

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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.

Notes:
Electrons revolve around the nucleus in specified circular paths called orbits or shells. Each orbit or shell is associated with a definite amount of energy. Hence these are also called energy levels and are designated K, L, M and N, respectively. The energy associated with a certain energy level increases with the increase of its distance from the nucleus. Hence if the energy associated with the K, L, M and N shells are E1, E2, E3……… respectively, then E1 < E2 < E3 ………. etc. As long as the electron revolves in a particular orbit, the electron does not lose its energy. Therefore, these orbits are called stationary orbits and the electrons are said to be in stationary energy states. An electron jumps from a lower energy level to a higher energy level, by absorbing energy, but when it jumps from a higher to lower energy level, the energy is emitted in the form of electromagnetic radiation. The energy emitted or absorbed (ΔE) is an integral multiple of “hν.”

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John Newlands, a British chemist, was the first person to devise a periodic table of chemical elements arranged in order of their relative atomic masses.

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Oxygen gas is colourless, odourless and tasteless. Colour of chlorine is yellow, sulphur is yellow and colour of phosphorous is white.

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Like many other things, milk contains bacteria, Milk also naturally contains a kind of sugar known as “lactose.” The bacteria that live in milk get energy from this special sugar and use it to reproduce to make even more bacteria. When the bacteria use the lactose sugars to reproduce, they change it from “lactose sugar” into “lactic acid,” which tastes sour.