States of Matter

Yes, when water is heated after reaching 100^oC water starts boiling. At this temperature water turns into vapour.

Yes, it is correct. The change of solid to liquid is called melting. The change of liquid to gas is called the vaporization. The change of gas into liquid is called condensation.

Yes, it is correct. Condensation takes place only on decreasing the temperature.

Impurities disrupt the regular crystal lattice structure of a pure substance, making it easier to break intermolecular bonds. This melting point depression means impure substances always melt at temperatures lower than their pure form's standard melting point.

Milk is a colloid mixture of water, fats (butterfat), proteins (casein), and sugars (lactose) that cannot be separated by simple filtration. Ice is pure H₂O, iron is a single element, and calcium oxide (CaO) is a pure compound; none are mixtures.

Melting ice is a physical change: only the state changes from solid to liquid while H₂O molecules remain unchanged (reversible). Cooking, butter turning rancid (oxidation), and burning all involve chemical reactions creating new substances with different properties (irreversible).

Distilled water is the purest form of water because it is produced by boiling water into steam and then condensing it back into liquid, leaving behind virtually all impurities, dissolved salts, and contaminants. Sea water contains high salt content, tap water may contain minerals and treatment chemicals, and bottled water like Bisleri undergoes purification but still contains some dissolved minerals compared to completely pure distilled water.

Sugar and milk forms a homogeneous mixture because sugar completely dissolves in milk, creating a uniform solution where you cannot see separate components or distinguish sugar particles from milk. The other options are heterogeneous: sand in water settles, sugar and sand remain as separate visible particles, and rice in water shows distinct solid particles in liquid.

Common salt (NaCl) is a pure compound, not a mixture, because it has a fixed chemical composition and consistent properties throughout - every part is identical NaCl. Sea water contains salt, minerals, and organic matter (mixture), air is a mixture of nitrogen, oxygen, CO2 and other gases, and pickle contains spices, oil, salt, water and other ingredients (mixture).

Condensation is the process where water vapour (gas) cools down and changes state into liquid water - this is what you see as water droplets on cold surfaces or clouds forming. Evaporation is the reverse (liquid to gas), crystallization is formation of solid crystals from solution, and sublimation is solid directly becoming gas without passing through liquid state.

Curdling is the breaking of an emulsion or colloid into large parts of different composition through the physico-chemical processes of flocculation, creaming and coalescence.

When a cold glass sits in warm air, water vapor in the air contacts the cold surface and condenses into liquid droplets on the outside. This is condensation - the same process that causes dew on grass. The water doesn't freeze, change color, or evaporate; droplets form on the exterior due to temperature difference.

When water is heated in a paper cup over a flame, the water absorbs the heat through conduction and convection. The water's boiling point (100°C) is well below the paper's ignition temperature (233°C or higher). As long as water remains in the cup, the paper cannot reach its ignition temperature, preventing it from burning.

Carbon dioxide gas is stored in metal cylinders in a liquid state under high pressure. When the valve is opened, the pressure drops and the liquid vaporizes into gas.