Matter & Mixtures — Set 2

Correct Answer: D. Oil and water

• **Immiscible liquids** = Oil and water form a heterogeneous mixture because they do not mix and form distinct layers. • **Visible separation** — The two phases can be clearly seen even without magnification. • 💡 Wrong-option analysis: A: Soda water is homogeneous with dissolved CO₂; B: Saltwater is homogeneous with dissolved salt; C: Vinegar is a homogeneous solution.

Correct Answer: D. Plasma

• **Plasma definition** = An ionized gas consisting of free electrons and positive ions in an electrically neutral overall state. • **Most abundant state** — Plasma exists in stars, lightning, and accounts for most of the visible universe. • 💡 Wrong-option analysis: A: Bose-Einstein Condensate is exotic state at near absolute zero; B: Liquid is a basic state; C: Gas is a basic state.

Correct Answer: B. Chromatography

• **Chromatography principle** = Separates components based on their different rates of movement through a stationary phase. • **Multiple types** — Paper chromatography, thin-layer chromatography, and gas chromatography are commonly used. • 💡 Wrong-option analysis: A: Sublimation is solid to gas conversion; C: Distillation separates by boiling point differences; D: Centrifugation separates by density differences.

Correct Answer: C. 4°C

• **4 degrees Celsius** = Water reaches its maximum density at this unique temperature. • **Anomalous expansion** — Below 4°C, water expands as it gets colder, which is why ice floats. • 💡 Wrong-option analysis: A: At 0°C water freezes but density is lower; B: At 100°C water boils with lowest density; D: Temperature below freezing point is not relevant.

Correct Answer: B. Immiscible

• **Immiscible liquids** = Liquids like oil and water do not mix to form a single phase due to molecular differences. • **Separate layers** — They form distinct layers with a clear boundary between them. • 💡 Wrong-option analysis: A: Saturated refers to maximum solute dissolved; C: Miscible liquids mix completely; D: Supersaturated has excess solute dissolved.

Correct Answer: A. Scattering of light by particles

• **Tyndall effect** = Scattering of a light beam by colloidal particles, making the beam visible in the solution. • **Particle identification** — The effect indicates presence of colloidal particles rather than true molecular solutions. • 💡 Wrong-option analysis: B: Absorption means light is taken in; C: Refraction is bending of light; D: Reflection is bouncing of light.

Correct Answer: A. 373 K

• **373 Kelvin** = Water boils at 100 degrees Celsius, which converts to 373 K using K = °C + 273. • **Pressure dependent** — This temperature applies only at standard atmospheric pressure of 101.325 kPa. • 💡 Wrong-option analysis: B: 0 K is absolute zero; C: 100 K equals -173°C; D: 273 K is freezing point of water.

Correct Answer: B. Centrifugation

• **Centrifugation method** = Rapid rotation separates particles of different densities using centrifugal force. • **Density separation** — Denser particles move outward while lighter particles move toward the center. • 💡 Wrong-option analysis: A: Crystallization forms solid crystals from solution; C: Filtration separates by particle size; D: Distillation separates by boiling point.

Correct Answer: B. Atom

• **Atom definition** = The basic building block of matter and the smallest unit of an element that retains chemical properties. • **Cannot be subdivided** — By chemical means, atoms cannot be further broken down into simpler units. • 💡 Wrong-option analysis: A: Molecules are formed from multiple atoms; C: Ions are charged atoms; D: Compounds contain multiple elements.

Correct Answer: A. Cutting paper

• **Cutting paper** = The chemical composition remains identical; only the shape and size change. • **Reversible nature** — Physical changes typically can be reversed by simply rearranging matter. • 💡 Wrong-option analysis: B: Burning wood produces new substances; C: Souring milk involves chemical change; D: Cooking egg involves chemical change.