Chemistry- 1 - SSC CGL Free MCQ Test with solutions

Plasma is a state of matter with ionized particles, found in stars and neon lights. Solids have both a definite shape and volume, making Statement 2 incorrect.

Chromatography separates mixture components based on their different rates of movement through a stationary phase under the influence of a mobile phase. Filtration separates solids from liquids, distillation separates liquids by boiling points, and sublimation separates solids that sublime.

Dalton’s atomic theory states that atoms of the same element are identical in mass and properties, though modern science recognizes isotopes (same element, different masses).

Electronegativity decreases down a group due to increased atomic size and shielding effect, and increases across a period due to higher nuclear charge.

Ionic bonds form between metals and non-metals through electron transfer. Covalent bonds involve electron sharing, not transfer, making Statement 2 incorrect.

This is a combination reaction, where two or more reactants (H₂ and O₂) combine to form a single product (H₂O). Decomposition breaks a compound, displacement involves element replacement, and double displacement involves ion exchange.

A neutral solution has equal concentrations of H⁺ and OH⁻ ions, resulting in a pH of 7 at 25°C. pH < 7 is acidic, and pH > 7 is basic.

Phenolphthalein is colorless in acidic or neutral solutions but turns pink in basic solutions (pH > 8). Litmus turns blue, methyl orange turns yellow, and universal indicator shows a range of colors.

Metals are malleable (can be shaped) and ductile (can be drawn into wires). However, not all metals are good conductors (e.g., mercury is a poor conductor of heat), making Statement 2 incorrect.

Rusting is the corrosion of iron, forming iron oxide due to reaction with oxygen and moisture. It is a chemical change, not physical, and involves oxidation, not thermal decomposition.

Graphite has a layered structure with weak van der Waals forces between layers, allowing them to slide, making it a lubricant. Diamond is hard, fullerene is cage-like, and graphene is a single layer.

Alkanes are saturated hydrocarbons with single bonds, following the formula CₙH₂ₙ₊₂ (e.g., methane: CH₄). Alkenes are CₙH₂ₙ, alkynes are CₙH₂ₙ₋₂.

Soaps are sodium/potassium salts of fatty acids, with a hydrophilic head and hydrophobic tail. They reduce water’s surface tension, enabling emulsification of grease, so both statements are correct.

Natural gas primarily consists of methane (CH₄). Ethane, propane, and butane are present in smaller amounts or used in LPG.

CFCs, used in refrigerants and aerosols, release chlorine atoms that catalyze ozone (O₃) breakdown in the stratosphere. The Montreal Protocol bans their use.

Fractional distillation separates petroleum into fractions (e.g., petrol, diesel, kerosene) based on differing boiling points. Air separation uses cryogenic distillation, and other options involve different methods.

Acid rain results from SO₂ and NOx forming sulfuric and nitric acids in the atmosphere, lowering rainwater pH. Acid rain has a pH below 5.6, not above 7, making Statement 2 incorrect.

Sodium hypochlorite (NaOCl), found in household bleach, is a bleaching agent due to its oxidizing properties. Sodium bicarbonate is baking soda, calcium carbonate is in chalk, and sodium chloride is table salt.

Ethanol (C₂H₅OH) contains a hydroxyl (-OH) group, characteristic of alcohols. Aldehydes have -CHO, ketones have C=O, and carboxylic acids have -COOH.

Combustion of methane releases heat, making it exothermic. Photosynthesis, electrolysis, and decomposition of calcium carbonate are endothermic, absorbing heat.