SSC CGL Previous Year Questions: Chemistry (2023-20) - 2 with solutions

Butyric acid (C₄H₈O₂). Propionic Acid (C₃H₆O₂) - A colourless liquid with a sharp rancid odour. It is a short-chain saturated fatty acid comprising ethane attached to the carbon of a carboxy group. Succinic Acid (C₄H₆O₄) - An alpha,omega-dicarboxylic acid resulting from the formal oxidation of each of the terminal methyl groups of butane to the corresponding carboxy group. Lactic Acid (C₃H₆O₃) - A colourless to yellow odourless syrupy liquid, Used to make cultured dairy products, as a food preservative.

Potassium bitartrate (KC₄H₅O₆) : Common Name - Cream of tartar. Uses - Additive, Stabilizer, pH control agent.

Ethynyl. An organic radical and a terminal acetylenic compound. Uses: Fuel, Industrial applications, Medical applications.

Fluorine - It is an univalent poisonous gaseous halogen; Pale yellow-green; Most chemically reactive and electronegative of all the elements.

Ethylene (C₂H₄): A colourless ammable gas with a faint ‘sweet and musky’ odour when pure, Simplest form of organic compounds and used in fruit ripening.

Galacturonic acid (C₆H₁₀O₇) - An acidifying agent in foods and the monomer of pectin molecules.

Glycerol (C₃H₈O₃) - A colourless, odourless, sweet-tasting, viscous liquid that is non-toxic. IUPAC name - Propane -1, 2, 3-triol.

Carboxylic acid (R−COOH) - an organic compound containing a carboxyl functional group. Example - acetic acid (CH₃COOH). Uses - manufacture of soaps, production of soft drinks and many other food products, in pharmaceuticals, and manufacture of nylon-6,6.

Diene is a covalent compound that contains two double bonds.

Carbon and its compounds get easily oxidised when subjected to combustion. For example alcohol on oxidation is converted to carboxylic acid. Hydrocarbons {Saturated, Unsaturated , Cycloalkanes, Aromatic, Aliphatic, and Alicyclic. Oxidation (gain of oxygen), Reduction (loss of oxygen), Redox reaction (oxidation and reduction occurring together).

Alkanes are a series of compounds that contain carbon and hydrogen atoms with single covalent bonds.

Paradichlorobenzene (C₆H₄Cl₂) is used as a fumigant insecticide to control cloth moths. Ethylbenzene (C₆H₅CH₂CH₃) is to manufacture styrene, a compound used to make plastics. Benzoyl chloride (C₇H₅ClO) is mainly useful for the production of peroxides. Chlorobenzene (C₆H₅Cl) is used primarily as a solvent, a degreasing agent, and a chemical intermediate.

Ethanol (CH₃CH₂OH) is used in the manufacture of drugs, plastics, lacquers, polishes, plasticizers, and cosmetics.

The melting point of graphite is slightly larger than the melting point of diamond because in graphite C-C bonds have a partial double-bond character and hence are stronger and more dicult to break.

3, 8. Propane is an alkane with the chemical formula C₃H₈ . As a type of hydrocarbon, it can undergo hydrocarbon combustion, which gives off heat.

120. Benzene is an organic chemical compound with the molecular formula C₆H₆ . The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each, where all the bonds are identical. It has the shape of a regular hexagon, with bond angles of 120°.

Be < Mg < Ca < Sr < Ba. Alkaline earth metals : Second most reactive family of elements, present in group 2 of the modern periodic table. Elements and their atomic number : Alkaline earth metals - Beryllium (4), Magnesium (12), Calcium (20), Strontium (38), Barium (56). Halogen (Group 17 or Group VIIA) - Fluorine (9), Chlorine (17), Bromine (35), Iodine (53). Oxygen family (Group 16 or Group VIA) - Oxygen (8), Sulphur (16), Selenium (34).

Nitrogen (N). Other elements with their atomic number: Silicon (Si, 14), Phosphorus(P, 15), Sulphur(S,16), Argon (Ar, 18), Potassium (K, 19), Scandium(Sc, 21), Titanium (Ti, 22), Calcium (Ca, 20), Chlorine (Cl, 17), Oxygen (O, 8).

1865. Law of Octaves - Every eighth element has similar properties when the elements are arranged in the increasing order of their atomic masses.

Actinium. It is a silvery radioactive metallic element that glows in the dark due to its intense radioactivity with a blue light. It was discovered in 1899 by André-Louis Debierne. Groups 3 to 12 elements are called d-block or transition elements.

18. Neon is an inert gas and element of the 18th group of the modern periodic table. Electronic conguration of some elements : Neon (Ne, Atomic number - 10) - [He], 2s²2p⁶ (the last orbit is completely lled). Lithium (Li, Atomic number - 3) - [He], 2s¹ (last orbit is not completely filled). Sodium (Na, Atomic number - 11) - 1s² , 2s² 2p⁶ , 3s¹ (or) [Ne] 3s¹ .

Francium (Fr): It is in liquid form at room temperature. Second-most electropositive element (after cesium).

Nihonium (Nh) - It is an extremely radioactive synthetic chemical element with a stable isotope, atomic mass - 286 u, has a half-life of 10 seconds and is a transactinide element in the p-block.

9, Fluorine (F). Group 17 (Halogen elements):- Chlorine (Cl, 17), Bromine (Br, 35), Iodine (I, 53), Astatine (At, 85), and Tennessine (Ts, 117).

Xenon. Period - A horizontal row of the periodic table. Total Period - 7 periods, with each one beginning at the far left. Group - A column of elements in the periodic table of the chemical elements. Total Groups - 18.