Chemistry MCQs

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Caesium is the least electronegative element in the periodic table and Fluorine is the most electronegative. Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.

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Photochromatic or Photochromic glass acquires a darker shade when exposed to bright light and returns to its original lighter shade in dim light. This happens because silver halides (iodide or chloride)  is added to this glass

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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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Calamine is an ore that contains zinc carbonate along with impurities like iron oxide. Through smelting, the zinc carbonate in calamine can be reduced to extract pure zinc metal. Other common zinc ores are sphalerite (zinc sulfide) and smithsonite (zinc carbonate). So calamine is considered a zinc ore due to its zinc carbonate content.

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A catalyst is a substance that increases the rate of a chemical reaction without undergoing any permanent change itself. At the end of the reaction, a catalyst retains its original quantity and chemical composition. This property allows it to be used repeatedly in reactions. For example, enzymes, which are biological catalysts, remain unchanged after facilitating biochemical reactions.

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Andesite is a type of volcanic rock that is intermediate in composition between basalt and rhyolite. It is typically gray to black in color and has a fine-grained, porphyritic texture, with larger crystals of feldspar and other minerals embedded in a finer-grained matrix. Andesite is formed when magma cools and solidifies at or near the Earth’s surface. It is common in volcanic arcs and other tectonically active areas, such as the Andes Mountains in South America, where it gets its name.
Andesite is typically less dense and more viscous than basalt, and it has a lower melting point. It is often intermediate in silica content between basalt and rhyolite, with a SiO2 content of around 53-62%. Andesite can also contain other minerals such as pyroxene, amphibole, and biotite, and it may exhibit a range of textural and compositional variations depending on the conditions under which it formed. Andesite is an important rock type in many geologic settings and is used in a variety of construction and landscaping applications.

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The main constituent of vegetable oil and animal fats is triglyceride. Triglycerides are composed of three fatty acids linked to a glycerol molecule. They are the most common type of fat found in the body and serve as a major energy source. In fact, triglycerides account for about 95% of the fats in the human diet.

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Aluminum is considered a “Green Metal” primarily due to its high recycling rate. Approximately 75% of all aluminum ever produced is still in use today, as it can be recycled indefinitely without losing quality. This process saves energy—recycling aluminum uses about 95% less energy than producing new aluminum from bauxite ore. Additionally, recycling reduces greenhouse gas emissions and conserves natural resources, making aluminum a sustainable choice in various applications.

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The correct answer is Mercury. An amalgam is a specific type of alloy that primarily consists of mercury mixed with another metal, commonly used in dental fillings due to its durability and ease of use. Historically, amalgams have been used since ancient times, with the earliest known use dating back to the 9th century in China.

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Third option is the correct answer
Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone.