Chemistry MCQs

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Nitrous oxide is often referred to as “Laughing Gas” due to the euphoric effect it produces when inhaled. Its chemical formula is N2O and it is an oxide of nitrogen. At room temperature, it is a colorless, non-flammable gas with a relatively sweet odor and taste. It is primarily used in dentistry and surgery for its analgesic and anesthetic properties. It is also noted for its role as a major greenhouse gas and air pollutant, as well as a natural regulator of stratospheric ozone.

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Avogadro’s hypothesis states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules. This principle is foundational in chemistry, leading to the concept of the mole, which is defined as (6.022 imes 10^{23}) entities (Avogadro’s number). This means that regardless of the type of gas, if the volume, temperature, and pressure are constant, the number of molecules will be the same.

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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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Both are oxidation-therefore exothermic processes

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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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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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Diethyl ether is a colourless, highly volatile & flammable organic compound. It was earlier used for anaesthesia but after the development of non-flammable drugs, its uses as anaesthetic has been reduced.

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5-8% solution of acetic acid in water is called vinegar and is used widely as a preservative in pickles

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Sodium carbonate is commonly known as Washing soda. Sodium Hydrogencarbonate is commonly known as Caustic soda. Ethanoic acid is commonly known as Acetic acid. calcium oxychloride is commonly known Bleaching powder.

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A solution of iodine in alcohol known as ‘tincture of iodine’, has iodine (solid) as the solute and alcohol (liquid) as the solvent.