Chemistry MCQs

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The Lysergic Acid Diethylamide (LSD) is a hallucinogenic drug. This drugs effects can last for up to 20 hours. The use of this drug is mainly done for recreational purposes or for spiritual reasons.

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Iodoform is the organoiodine compound with the formula CHI3. A pale yellow, crystalline, volatile substance, it has a penetrating odor and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant. Adolf Hitler’s mother, Klara Hitler, died of iodoform poisoning brought on by her treatment for breast cancer.

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Quantum numbers may be defined as a set of four numbers which give complete information about the electron in an atom, i.e., energy, orbital occupied, size, shape and orientation of that orbital and the direction of electron spin. Magnetic quantum number is required to explain the fact that when the source giving the line spectrum is placed in a magnetic field, each spectral line splits in to a number of lines. The magnetic quantum number tells the number of orientations which the orbitals present within the same sub-shell can take up.

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Sublimation is a type of phase transition, or a change in a state of matter, just like melting, freezing, and evaporation. Through sublimation, a substance changes from a solid to a gas without ever passing through a liquid phase. Camphor and Dry ice (solid CO2) provide a common example of sublimation.

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The law of definite proportion, sometimes called Proust’s law, states that a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation. For example, oxygen makes up about 8/9 of the mass of any sample of pure water, while hydrogen makes up the remaining 1/9 of the mass.

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Valency is number of electrons gain or loss to achieve noble gas configuration I.e. fully filled octet. Magnesium (Atomic number = 12) has electronic configuration 2, 8, 2. Since magnesium has 2 electrons in its outermost shell, hence it’s valency is 2, i.e., it will lose it’s 2 electrons to achieve noble gas configuration (2,8).

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Malachite (Cu2CO3(OH)2 is a green, very common secondary copper mineral with a widely variable habit. It is a copper carbonate hydroxide mineral. Typically, it is found as crystalline aggregates or crusts, often banded in appearance, like agates. It is also often found as botryoidal clusters of radiating crystals, and as mammillary aggregates as well.

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Tungsten, a chemical element with symbol W, is used in incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, super-alloys, and radiation shielding. It has the highest melting point of all the elements discovered, melting at 3422 °C (6192 °F, 3695 K). It also has the second highest boiling point, at 5930 °C.

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Bakelite is a poor conductor of heat and electricity. It is a thermosetting plastic that has very high internal resistance that resist the circuit current flow through it. One of the first plastics made from synthetic components, it was used for its electrical non–conductivity and heat-resistant properties in electrical insulators and products such as kitchenware, jewelry, children’s toys, firearms, etc.

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The conversion of water into steam is an example of a physical change, where the state of the matter changes without changing its composition. A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.