Answer: A is likely a colloid (shows Tyndall effect, beam visible and turbidity), examples: milk or diluted milk. B is a true solution (no Tyndall effect), e.g., sugar solution. The Tyndall effect distinguishes colloids from true solutions because colloidal particles scatter light.

Answer: (1) Use a magnet to remove iron filings (magnetism). (2) Add water to remaining sand + salt; salt dissolves (solubility). (3) Filter to separate sand (filtration). (4) Evaporate filtrate to obtain salt (evaporation/crystallization). Each step exploits a different physical property ensuring efficient separation.

Answer: Dissolved salts are invisible and do not affect clarity; thus water can look clear but be saline. To test at home, evaporate a measured volume of water on a clean plate—residue indicates dissolved salts. Alternatively, use a conductivity meter; high conductivity indicates dissolved ions. For reliable removal, distillation or reverse osmosis is recommended.

Answer: The spot that travelled farther has greater affinity for the mobile phase (solvent) and less affinity for the paper (stationary phase). The slower spot has more affinity for the stationary phase. Rf values reflect these affinities; higher Rf = more soluble in mobile phase.

Answer: Clarify juice by filtration and coagulation to remove suspended impurities. Concentrate by evaporation to form a saturated syrup, then allow controlled cooling to promote crystallization of sugar. Collect crystals by centrifugation or filtration and dry. Crystallization yields purer sugar as impurities remain in mother liquor.

Answer: Use a simple sublimation setup: place mixture in a china dish, cover with an inverted funnel whose stem leads to a cooled receiver or watch glass placed upside down. Heat gently; camphor sublimes and condenses on the cooler surface. Collect camphor crystals. Principle: sublimation. Ensure gentle heating and proper ventilation.

Answer: Passing through a fine membrane likely removed colloidal particles (or aggregated them), converting the sample into a clearer solution or very dilute colloid that no longer scatters light. If particles were removed, the Tyndall effect disappears because scattering centers are absent.

Answer: Ethanol and water form an azeotrope at ~95% ethanol which boils at a constant composition; fractional distillation cannot break this azeotrope. To obtain absolute ethanol, use drying agents (like molecular sieves), azeotropic distillation with another reagent, or chemical methods to remove water. Molecular sieves adsorb water allowing attainment of ~100% ethanol.

Answer: Use vacuum filtration (Buchner funnel with suction) to speed up. Alternatively, pre-coat the filter with a layer of glass wool or sand to prevent clogging, use larger pore filter paper for coarse particles, or allow coarse particles to settle (decant) before filtration. Stirring gently and avoiding overloading also helps.

Answer: Centrifugation is used—spinning blood in a centrifuge applies centrifugal force causing denser red blood cells to sediment while plasma remains as supernatant. This rapid separation based on density differences is essential for clinical analyses.

Answer: Heating may temporarily mix immiscible liquids (if emulsified) and could create stable emulsions making separation harder. The correct method is to use a separating funnel to allow layers to settle and then decant the denser lower layer. If an emulsion forms, add salt or centrifuge to break it, not heating indiscriminately.

Answer: First remove suspended clay by sedimentation and filtration or coagulation followed by filtration. Then remove dissolved salts by distillation or reverse osmosis. Coagulation (adding alum) aggregates fine particles making filtration easier. A two-stage process targets suspended solids first, then dissolved ions.

Answer: Change the solvent system (mobile phase) to alter relative affinities, use longer chromatography paper to increase travel distance, try thin-layer chromatography with different stationary phase, or adjust temperature. Optimizing solvent polarity often resolves overlapping spots.

Answer: Evaporation of seawater leaves salt plus other dissolved inorganic impurities and minerals, causing bitterness. To obtain purer salt, dissolve residue in minimal water, filter to remove insolubles, then perform crystallization by slow cooling to get purer NaCl crystals; discard mother liquor containing impurities. Recrystallization improves purity.

Answer: Stating the principle demonstrates conceptual understanding and justifies the choice of method. Example: For separating sand and salt, stating 'filtration exploits insolubility of sand while salt dissolves' shows why filtration followed by evaporation is appropriate. Examiners award marks for principles as they reflect reasoning beyond procedural steps.

Answer: Perform Tyndall test: shine a narrow beam of light through the sample in a dark room. If the beam is visible (light scattered), it's a colloid; if not, it's a true solution. Alternatively, allow sample to stand—colloids usually don't settle while suspensions do.

Answer: Use centrifugation to sediment the fine particles, then decant supernatant and filter remaining coarse particles. Alternatively, coagulate the colloidal particles (by adding appropriate electrolyte) to form larger aggregates that can be filtered.

Answer: A constant temperature indicates that a component (or azeotropic mixture) with a fixed boiling point is vaporizing; energy is used for phase change rather than increasing temperature. This helps identify boiling points of components and signals when a particular fraction is being collected.

Answer: Use adsorption-based concentration like solid-phase extraction or simple evaporation to concentrate dye if heat-stable; for analysis, paper or thin-layer chromatography separates components and allows identification. For fastest lab-scale preconcentration, evaporate solvent under reduced pressure (rotary evaporation) if available.

Answer: Solution: Homogeneous mixture with molecular/ionic solute—no Tyndall effect (e.g., salt solution). Colloid: Particles 1–1000 nm, do not settle, show Tyndall effect (e.g., milk). Suspension: Large particles, settle on standing (e.g., muddy water). Quick tests: Tyndall effect to detect colloid; allow to stand—suspension settles; filtration—suspension particles are retained, solutions pass through. State examples and tests clearly for full marks.