Chemistry MCQs

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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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chemical oxygen demand is a measure of water quality and is amount of organic pollutants found in surface water. Potassium permanganate has been used for many years to measure COD

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Sodium benzoate is commonly used as a preservative in food and beverages, including tomato juice. It inhibits the growth of mold, yeast, and some bacteria, extending shelf life. It is effective in acidic environments, such as those found in tomato products, where the pH is typically below 4.6. Sodium chloride (salt) can also act as a preservative but is primarily used for flavor. Sodium carbonate and sodium lauryl sulfate are not suitable preservatives for tomato juice.

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The Mizoroki-Heck reaction is a cross-coupling reaction that typically involves the coupling of aryl halides with alkenes. It is primarily catalyzed by palladium (Pd) complexes. Palladium is favored due to its ability to facilitate the oxidative addition and reductive elimination steps essential for the reaction. Rhodium, while also a transition metal, is less commonly used for this specific reaction. The Mizoroki-Heck reaction is important in organic synthesis for forming carbon-carbon bonds and is widely utilized in pharmaceuticals and materials science.

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A baby diaper can absorb the maximum quantity of distilled water as it lacks impurities such as minerals and ions that are present in other type of water. The absorbent materials in diapers, often polymers called sodium polyacrylate, can hold up to 30 times their weight in distilled water, making them highly efficient.

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The chemical name of Quick Lime is Calcium Oxide (CaO).

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Fractional distillation method is used to separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K. example: Air, crude oil, chlorosilanes etc.

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Epsom salt is an ore containing Magnesium. It is also known as the heptahydrate sulfate mineral. Its chemical formula is MgSO₄·7H₂O.

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Silicon has an atomic number 14 and the outer electronic configuration is 3s² 3ps². It is placed at the 3rd Period and 14th Group number.

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pH scale is a scale for measuring hydrogen ion concentration in a solution, called pH scale has been developed. The p in pH stands for ‘potenz’ in German, meaning power. On the pH scale we can measure pH generally from 0 (very acidic) to 14 (very alkaline). The pH of a neutral solution is 7. Values less than 7 on the pH scale represent an acidic solution.