Chemistry MCQs

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Brass is an alloy of Copper and Zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. The proportions of Zinc and Copper can vary to create different types of brass alloys with varying mechanical and electrical properties.

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Potassium permanganate is a point-of-entry treatment method that oxidizes dissolved iron, manganese, and hydrogen sulfide into solid particles that are filtered out of the water. It can also be used to control iron bacteria growth in wells.

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Sodium sulfate, used as a filler in detergent powder, enables the adjustment of the concentration of the active matter in the detergent, as required.

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Cassiterite is a mineral that is primarily composed of tin dioxide (SnO2). It is the most important source of tin, and is also used as a semi-precious gemstone. Cassiterite is typically found in igneous and metamorphic rocks, and is often associated with other minerals such as quartz, feldspar, and mica. It has a high melting point and is resistant to weathering, making it a useful material for many industrial applications. The name “cassiterite” comes from the Greek word “kassiteros,” which means “tin.”

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Pewter is primarily composed of tin, typically around 85-95%, with the remainder often consisting of copper, antimony, or bismuth. Historically, pewter was used for making utensils and decorative items due to its malleability and low melting point. The use of tin in pewter dates back to ancient civilizations, including the Romans and Egyptians, who valued it for its corrosion resistance and ease of casting.

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Under ordinary conditions on Earth, elemental hydrogen exists as the diatomic gas, H2. However, hydrogen gas is very rare in the Earth’s atmosphere (1 ppm by volume) because of its light weight, which enables it to escape from Earth’s gravity more easily than heavier gases. However, hydrogen is the third most abundant element on the Earth’s surface, mostly in the form of chemical compounds such as hydrocarbons and water. Hydrogen gas is produced by some bacteria and algae and is a natural component of flatus, as is methane, itself a hydrogen source of increasing importance.

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Sievert’s law is used as a rule in physical metallurgy to predict the solubility of gases in metals.

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Amalgam is the general name given to an alloy of mercury with some other metal. It can be a solid, liquid or a soft paste depending on the composition of the constituents.

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Alumina is the common name given to aluminum oxide (Al²O³). It is produced from bauxite to get pure aluminium metal.

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The total number of nucleons is termed as mass number (A) of the atom. In this case, mass number is 80. Therefore, sum of the number of neutrons and protons is 80. As atomic number is 35, we know that number of protons is 35. Hence, number of neutrons = 80-35 = 45.