Chemistry MCQs

Notes:
Tartaric acid occurs naturally in many fruits such as grapes, bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of winemaking. It is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. The acid itself is added to foods as an antioxidant E334 and to impart its distinctive sour taste.

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Radium is a chemical element with the symbol Ra and atomic number 88. Radium was discovered by Marie Sklodowska Curie, a Polish chemist, and Pierre Curie, a French chemist, in 1898.

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Cinnabar, also known as mercurblende, is indeed the most common ore source for refining elemental mercury. However, its color range runs from scarlet to brick-red, not grey to green. It is known for providing the brilliant red or scarlet pigment known as vermilion, not a blue pigment.

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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.

Notes:
The correct answer is Octaoxygen. Octaoxygen (O8) is an allotrope of oxygen that can exist in multiple phases under varying pressures and temperatures. It was first synthesized in 2001 and is notable for its unique molecular structure, which consists of eight oxygen atoms. Ozone (O3) is well-known but does not exhibit multiple phases like octaoxygen. Tetraoxygen (O4) is less stable and not commonly referenced in the same context.

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Potassium graphite and calcium graphite are primarily used as superconductors. Superconductors are materials that can conduct electricity without resistance when cooled below a certain temperature. Graphite, particularly when doped with potassium or calcium, exhibits enhanced superconducting properties. Notably, the discovery of high-temperature superconductors in the 1980s revolutionized the field, leading to applications in magnetic levitation and advanced electronic devices.

Notes:
Helium has the lowest boiling point of all the elements at –452.074°F (–268.93°C) followed by hydrogen –423.16°F (–252.87°C). The highest boiling point for an element is that of Rhenium 10,104.8°F (5,596°C) followed by tungsten 10,031°F (5,555°C).

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Silver halides and most commonly silver Chloride is used in Photochromic lens. But for plastic photochromic lenses, some organic products such as oxazines and naphthopyrans are used.

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Ionization energy is the quantity of energy required to remove loosely bound electron from an atom.

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Newland law of octaves states that If the elements are arranged in order of their increasing atomic weights, every 8th element had similar properties to the first one. It was similar as the first and eighth note in music.