Chemistry MCQs

Notes:
The carat is the common unit used to describe the mass of a gem. A 1-carat diamond, for example, has a mass of 0.20 g. The karat is the common unit used to describe the purity of a precious metal, such as gold. A 24-karat gold ring is as pure as can be. A gold ring that is 50 % pure is 12 karat.

Notes:

Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. When oxidation occurs, an element loses electrons and its oxidation number increases .i.e. it becomes more positive.

Notes:
LPG is composed hydrocarbons containing three or four carbon atoms. The normal components of LPG thus, are propane (C₃H₈), butane (C₄H₁₀) and Methane (CH₄). Small concentrations of other hydrocarbons may also be present.

Notes:
CaMgO4Si is the chemical formula of calcium magnesium silicate . Calcium magnesium silicate is commonly known as Asbestos. Asbestos is a fibrous silicate mineral as the substance is formed by miniature crystal fibers, these crystal are loosely attached releasing dust of silicate crystal upon small touch.

Notes:
Electronegativity is defined as an atom’s ability to attract an electron pair when forming a covalent bond. This property increases as you move left to right across the periodic table due to an increase in the nuclear charge’s attractive forces. It decreases as you move top to bottom, owing to the shielding effect of sub-levels and increased atomic radius, which makes electrons easier to remove. This culminates in Fluorine, being the highest and furthest to the right on the periodic table, hence it is the most electronegative.

Notes:
Barium Sulphate is the correct answer. It is used as a radiopaque contrast agent in X-ray imaging because it absorbs X-rays, making it visible on the images. Commonly referred to as “Barium Meal” when ingested for gastrointestinal studies, it helps diagnose conditions like ulcers and tumors. Barium Sulphate is insoluble in water, ensuring it remains in the digestive tract without being absorbed.

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The carbon content of Kerosene is higher than the other fuels mentioned in the option, that is why it will emit maximum mass of carbon dioxide, when the same quantity is burnt.

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The scattering of a beam of light by the particles of a colloid is called the Tyndall effect.

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The dye from water can be separated by the method of evaporation. Evaporation is used to separate the volatile component (solvent) from its non-volatile solute.

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Field’s metal is an alloy of bismuth, indium, and tin, with the following percentages by weight: 32.5% Bi, 51% In, 16.5% Sn. Dutch metal, Prince’s metal and Muntz metal are a form of brass.