Test: SSC CGL Previous Year Questions: Chemistry (2023-20) - 3 - SSC CGL MCQ

Uranium. Atomic number - 92, Symbol - U. The heaviest man made element - Oganesson with atomic number 118, Atomic weight - 294, Symbol - Og. Hydrogen is the lightest element with atomic number - 1, Symbol - H, atomic weight - 1.0078. Xenon: Symbol - Xe and Atomic number - 54, Atomic weight - 131.29. Helium: symbol - He and atomic number - 2, atomic weight - 4.0026.

Helium - It is a noble gas with Atomic number - 2, Atomic mass - 4, Symbol - He. Some Noble elements: Argon (Ar) - Atomic number 18, Krypton (Kr) - Atomic number 36, Neon (Ne) - Atomic number 10, Xenon (Xe) - Atomic number 54, Radon (Rn) - Atomic number 86, Oganesson (Og) - Atomic number 118. Other Elements: Nitrogen (N) - Atomic number 7, Scandium (Sc) - Atomic number 21, Cobalt (Co) - Atomic number 27.

Group 17 (halogens) - Highly electronegative Non-metals {fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At)} with -1 oxidation state.

Alkali metals (Group 1). They are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr).

Lithium. Atomic radius is the total distance from the nucleus of an atom to the outermost orbital of its electron. It increases from top to bottom in a group and decreases from left to right across a period. Thus, helium is the smallest element, and francium is the largest.

Group 9 elements - cobalt, rhodium, iridium and meitnerium.

Metallic character decreases across a period and increases down the group.

16. The atomic mass of oxygen is 16 and atomic number 8. Joseph Priestley discovered Oxygen. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe.

11 . These elements are Hydrogen, Helium, Nitrogen, Oxygen, Fluorine, Chlorine, Neon, Argon, Krypton, Xenon, and Radon.

d-block or transition elements. They are called d block elements because their valence electron falls in the d-orbital.

Noble gases. In the periodic table, the highly electronegative halogens (group 17) and the highly electropositive alkali metals (group 1) are separated by noble gases which are present in group 18.

Helium (He). Atomic number - 2, Group - 18 (Noble gas), Block - S, chemically inert. Other uses of Helium - To keep satellite instruments cool, for arc welding, to provide an inert protective atmosphere for making bre optics and semiconductors.

22.4 litre . The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. PV = nRT, Where P = Pressure, V = Volume, n = Amount of Substance, R = Ideal Gas Constant, T = Temperature.

Tungsten (also called wolfram). Carbon is capable of forming many allotropes (structurally different forms of the same element) due to its valency. Buckminsterfullerene (C₆₀) is a spherical carbon allotrope where 60 atoms are assembled in pentagons and hexagons, in a geometry similar to a soccer ball.

Nitrogen. A decomposition reaction is a chemical reaction in which one reactant breaks down into two or more products. It can be both endothermic or exothermic. Lead Nitrate Pb(NO₃)₂ on decomposition Produces Lead oxide (PbO), Oxygen molecule (O₂), and Nitrogen dioxide (NO₂). Balanced Chemical equation - 2 Pb(NO₃)₂ → 2 PbO + 4 NO₂ + O₂ .

Both I and II. Boiling Point in Celsius: Chloroform (CHCl₃) : 61.2°C and Methane (CH₄) is -161.5°C. Some chemical elements and boiling points: Lowest boiling point element : Helium (-269°C). Aluminium (2467°C), Chlorine (-34.04°C), Bromine (58.8°C). In the absence of other intermolecular forces, the higher the molecular weight of a compound, the higher its boiling point.

Oleic acid (C₁₈H₃₄O₂) - A mono-unsaturated omega-9 fatty acid found in various animal (chicken and turkey) and vegetable sources (soybean oil, palm oil and corn oil); uses - An excipient in pharmaceuticals and as an emulsifying or solubilizing agent in aerosol products.

Calcium hydrogen carbonate {CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂}. The reaction proceeds at room temperature. It is used as an antacid to alleviate heartburn, acid indigestion. Apricot, gooseberry, gs and raisins are fruits rich in calcium. Calcium oxide (CaO), Calcium hydroxide {Ca(OH)₂}, Hydrochloric acid (HCl, strong acid).

Cyanide ion - CN^– are chemical compounds which are fast acting poisons with a chemical formula CN− . An ammonia molecule can bind another proton (H⁺) and become an ammonium iron, NH₄⁺ . A bromide ion is the negatively charged form (Br⁻) of the element bromine. Fluoride ion (F^-) is the simplest inorganic, monatomic anion of fluorine with basic properties.

Beryllium is an element with an atomic number of 4 in the periodic table. It is a bivalent and highly toxic element. The element has one of the highest melting points among the light metals. Beryllium is used as an alloying agent. It is relatively soft and has a low density. It is used in alloys with copper or nickel to make gyroscopes, springs, electrical contacts, spot-welding electrodes and non-sparking tools.

Water. A polar molecule is a molecule containing polar bonds where the sum of all the bond's dipole moments is not zero. Examples of Polar Molecules: Water (H₂O), Ethanol (C₂H₅OH), Ammonia (NH₃), Sulphur dioxide (SO₂), Hydrogen sulphide (H₂S).

Solution, salt water, brass. There are two types of mixtures: Homogeneous and heterogeneous. A mixture is a material composed of two or more simpler substances. Examples of homogeneous - Air, Wine, Vinegar, Coffee, Natural gas, Steel. Examples of heterogeneous - Oil and water, Concrete, Orange juice with pulp, Sandy water, Cereal in milk, A sandwich, Blood.

2.5% H, 39% S, 58.5% O. Sulfurous Acid (H₂SO₃) - Dihydrogen trioxosulphate or trioxo sulphuric acid. Mass - 82.07 g/mol. Percent composition = (mass of element / molecular mass) x 100. Composition of other compounds: Sulfuric acid (H₂SO₄) - 2.01 % H, 32.5 % S, 65.3 % O, Sodium carbonate (Na₂CO₃) - 43.40% Na, 11.32% C, 45.28% O.

A - 3, B - 1, C - 4, D - 2. Chemical Constituents of spices : Coriander - Linalool, borneol, terpineol, cumene. Saffron - Crocins, safranal, salicylic, vanillic acid. Mustard seeds - Allyl isothiocyanate. Garlic - Allicin. Ginger - Gingerol. Cumin - Cumin aldehyde.

Aqua Regia. It is used for purification purposes of gold and platinum. It is a mixture of nitric acid (HNO₃) and hydrochloric acid (HCl) in the ratio of 1:3. Sodium Nitrate (Chile Saltpetre) - NaNO₃. Vinegar (Acetic acid) - CH₃COOH. Sodium Chloride (Salt) - NaCl.

Kaolinite (Al₂Si₂O₅(OH)₄): A clay mineral. It's commonly found in soils and sedimentary rocks. Used in - Rubber, paint, paper making, and as a filler in some products. Orthoclase (KAlSi₃O₈): A common type of feldspar mineral (a group of rock-forming minerals). Magnesite (MgCO₃). Gypsum (CaSO₄·2H₂O): It is added to cement to slow down the rate of setting.