SSC CGL Previous Year Questions: Chemistry (2023-20) - 5 with solutions

Methyl chloride (CH₃Cl). It is also known as Chloromethane. It is a clear, colourless gas. It has a faint, sweet odour. It is heavier than air, and it is extremely flammable. It is used primarily in the manufacture of silicones, but was formerly used as a refrigerant and anaesthetic.

Nitric acid (HNO₃) - A colourless liquid with yellow or red fumes with an acrid odour. It is a highly corrosive liquid (Freezing point −42 °C [−44 °F], Boiling point 83 °C [181 °F]). Used: Manufacture of fertilisers, dyes, and explosives and also in the polymer industry.

3-Bromopropene - Organic halide used in the synthesis of polymers, pharmaceuticals, synthetic perfumes and other organic compounds.

Tetrahydrofuran (C₄H₈O). Other synonyms: Butylene oxide, Tetramethylene oxide. The compound is classified as a heterocyclic compound, specifically a cyclic ether. It is a colourless, water-miscible organic liquid with low viscosity

2-Propen-1-Amine (C₃H₇N). International union of pure and applied chemistry (IUPAC) : Established - 1919. It is responsible for maintaining the periodic table. 118 conrmed elements in the periodic table.

Une. International Union of Pure and Applied Chemistry (IUPAC) - It is the world authority on chemical nomenclature as well as terminology. It is basically a method of naming organic compounds according to certain rules, Established - 1919, Headquarters - North Carolina (United States).

Acrolein (C₃H₄O): It is a colourless to pale yellow liquid with a strong, pungent odour. Uses:- Used as a biocide to control plants, algae, molluscs, fungi, rodents, and microorganisms.

-ide. Example of some ions :F^- Fluoride, O^2- Oxide, Cl^- Chloride. − Polyatomic positive ions often have common names ending with the suffix -onium, Example - H₃O⁺ - Hydronium, NH₄⁺ - Ammonium.

2CaSO₄.H₂O [Gypsum Plaster] is a white dry plaster powder. It is prepared by heating calcium sulfate dihydrate (gypsum) to 120–180 °C. Uses: for setting fractured bones, in dentistry to make casts, making toys, decorative materials, cheap ornaments, cosmetics, and for protection as fire-proofing material.

Potassium Nitrate (KNO₃, Saltpetre) is an ionic white crystalline salt made up of potassium ions and nitrate ions. Uses - Main constituents of gunpowder, food preservatives and additives (in meat and sh), fertilizer, and oxidizer for reworks and rockets, etc.

Benzene. CH₃OH - Methanol, CH₃COOH - Acetic Acid, C₃H₆O - Acetone.

Iron chromium oxide. Chromite is used as a refractory in the production of steel, copper, glass, and cement. Chromite occurs as a primary accessory mineral in basic and ultrabasic igneous rocks.

Saponification value - It is the number of milligrams of potassium hydroxide (KOH) required to neutralize the fatty acids obtained by complete hydrolysis of one gram of fat or oil.

Zinc. Galvanization protects steel and iron from rusting and is commonly used in construction, pipes, and automotive parts to prevent corrosion, while adding a small amount of carbon to pure iron increases its strength and hardness. The reason that the galvanizing process uses zinc instead of other metals is that zinc oxidizes and experiences acid corrosion “sacrificially” to steel.

Vulcanisation. This process was discovered by Charles Goodyear. Saponification is the process of converting fats and oils into soap. Fermentation is the process of converting sugar into alcohol or other products. Carbonation is the process of dissolving carbon dioxide in a liquid.

Six. Sodium chloride crystal (NaCl), where ions taking part are Na⁺ and Cl^- . They have 1:1 stereochemistry and thus the coordination number of 6.

Gas. Particles have the highest kinetic energy when they are in the gaseous state. The highest force of attraction is among solids followed by liquid and then the gas, therefore the particles of gas are free to move.

Titania. Titanium dioxide, also called titania, (TiO₂), a white, opaque, naturally occurring mineral existing in a number of crystalline forms, the most important of which are rutile and anatase. It is used in paints, coatings, papers, inks, toothpaste, face powder, and food colouring.

pollutants namely particulate matter (PM) 10, PM 2.5, Ozone (O₃), Sulphur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), lead (Pb) and ammonia (NH₃) act as major parameters in deriving the AQI of an area.

Amino acid. Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. The amino acids link to form proteins.

Brownish. Iron Nail is Fe and blue copper sulphate is CuSO₄ . When nail is kept in it, Fe being more reactive than copper, it displaces copper from Copper sulphate and forms Ferrous Sulphate which is greenish blue, and the copper displaces deposits around nails giving it colour of reddish brown.

Manganese dioxide. Sodium Permanganate is produced by using Manganese dioxide to remove green from glass that results from the presence of Iron.