Chemistry MCQs

Notes:
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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Acetic acid (CH3COOH) is a weak organic acid that gives vinegar its sour taste. At household concentrations (5-8% acetic acid), it is a mild acid. Vinegar can be made from a variety of base ingredients including wine, apple cider, rice, or malt. The acetic acid is produced by fermentation of the sugars in these ingredients. The most common type of vinegar in households is white distilled vinegar which is typically 4-7% acetic acid. It has a strong, pungent smell and flavor.

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MTBE is a gasoline additive, used as an oxygenate to raise the octane number. Its use is controversial in the US and declining in that country in part because of its occurrence in groundwater and legislation favoring ethanol.

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Cobalt Oxide is commonly used to create a distinctive blue hue in glasses and ceramics. The depth of the blue can be altered by changing the concentration of the oxide. In addition to being used for aesthetic purposes, Cobalt blue, which results from Cobalt Oxide, is also used because it absorbs certain wavelengths of light, making it useful for filtering out unwanted wavelengths.

Notes:
Transuranic elements are those with atomic numbers greater than 92, which is the atomic number of uranium. These elements, including plutonium (94) and americium (95), are all synthetic and typically unstable, often used in nuclear applications and research. The term “transuranic” specifically refers to elements beyond uranium in the periodic table.

Notes:
Sublimation is the process where a solid turns directly into a gas without passing through the liquid phase.

• Iodine: Sublimes at about 113.7°C, releasing purple vapors.
• Naphthalene: Sublimes at around 80°C, commonly used in mothballs.
• Camphor: Sublimes at approximately 175°C, used in medicinal and aromatic applications.

All three substances can undergo sublimation upon heating, making the correct answer “All of them.”

Notes:
Ilmenite (FeO.TiO2) is important titanium mineral. It is widely distributed along the Indian coastal lines. With proven reserves exceeding 270 million tonnes, about 37 per cent of the total world Ilmenite reserves are located in the beach sands of the southern peninsular India. Titanium known for its excellent corrosion resistance, high strength and low density, is widely used for aero-engine and airframe structures in both civilian and military aircraft. Titanium-alloy components also find applications in satellite launch vehicles, rockets and missiles. As of now, India’s total titanium requirement is being met by imports even though it possesses a large reserve base of titanium minerals.

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Ankylosing Spondylitis is a chronic, inflammatory arthritis and autoimmune disease that mainly affects joints in the spine and the sacroiliac joints in the pelvis. It tends to affect the spine and in late stages, the spine will fuse and this has given rise to the term “bamboo spine”. It is mainly caused due to impurities in drinking water associated with fluorides.

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Bleaching powder is made by passing Cl2 into slaked lime. Though bleaching powder is often written as Ca(OCl)₂ , it is really a mixture and not a compound.

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It is used for softening of water, laundering, cleaning, manufacture of glass, soap, borax, paper, paints and textile It is also extensively used as laboratory reagent.