Matter in Our Surroundings – Practice Flashcards

A comprehensive set of question-and-answer flashcards covering definitions, properties, processes, and examples related to matter, its particle nature, states, interconversion, and evaporation as presented in the lecture notes.

What two fundamental properties do all forms of matter possess?

Mass and volume (they occupy space and have mass).

According to early Indian philosophers, which five basic elements (Panch Tatva) make up all matter?

Air, earth, fire, sky (space) and water.

What experiment with salt dissolved in water demonstrates about the physical nature of matter?

Salt particles occupy spaces between water particles, showing that matter is particulate, not continuous.

Why does a small crystal of potassium permanganate colour a large volume of water on successive dilutions?

Because each crystal contains millions of tiny particles that keep dividing and dispersing, illustrating the extremely small size of matter’s particles.

What term describes the constant, random movement of particles in matter?

Kinetic energy of particles (particles are continuously moving).

What is diffusion?

The intermixing of particles of two substances on their own, due to particle motion and spaces between them.

How does temperature affect the rate of diffusion?

Higher temperature increases kinetic energy, causing particles to move faster and diffuse more quickly.

What evidence shows that particles of matter attract each other?

Solids are difficult to break or compress, liquids form droplets/surfaces, and solids like iron nails resist breaking, indicating intermolecular attractions.

List the three common states of matter.

Solid, liquid and gas.

Give three key properties of solids.

Definite shape and volume, negligible compressibility, and rigidity (strong intermolecular forces).

Why is a rubber band still considered a solid even though it changes shape when stretched?

It regains its original shape after the force is removed, and excessive force only breaks it rather than causing permanent flow.

Why does a sponge compress even though it is a solid?

It contains minute air holes; pressing expels air, allowing compression without changing the solid framework.

State two characteristic properties of liquids.

Fixed volume but no fixed shape; they flow and take the shape of their container (fluidity).

Why do aquatic organisms survive underwater regarding gases?

Oxygen and carbon dioxide from the atmosphere diffuse and dissolve in water, enabling respiration for aquatic life.

Why are gases highly compressible compared to solids and liquids?

Gas particles are far apart with negligible attractive forces, so external pressure can greatly decrease their volume.

What causes gas pressure on the walls of a container?

Particles moving randomly at high speed collide with the walls, exerting force per unit area (pressure).

Define melting point.

The temperature at which a solid changes into a liquid at atmospheric pressure (for ice, 273.15 K or 0 °C).

What is latent heat of fusion?

The amount of heat energy required to convert 1 kg of a solid into liquid at its melting point without temperature change.

Define boiling point.

The temperature at which a liquid starts converting to vapour throughout its bulk at atmospheric pressure (for water, 373 K or 100 °C).

State the latent heat of vaporisation.

The heat energy required to change 1 kg of a liquid into vapour at its boiling point and atmospheric pressure.

What is sublimation?

Direct conversion of a solid to a gas without passing through the liquid state (e.g., camphor, naphthalene).

What is deposition (in matter change)?

Direct conversion of a gas to a solid without becoming a liquid.

Why is solid CO₂ called ‘dry ice’?

Because it sublimates directly to CO₂ gas at 1 atm without leaving liquid residue.

How can gases be liquefied?

By applying high pressure and/or lowering temperature to bring particles closer and reduce kinetic energy.

What is the Kelvin-to-Celsius conversion relation?

T(°C) = T(K) – 273; conversely, T(K) = T(°C) + 273.

Define evaporation.

Surface phenomenon where particles with higher kinetic energy escape from a liquid into the vapour phase at any temperature below boiling point.

List four factors that increase the rate of evaporation.

(1) Larger surface area, (2) higher temperature, (3) lower humidity, (4) greater wind speed.

Why does evaporation cause cooling?

Escaping particles take away latent heat, so remaining liquid and surroundings lose energy, resulting in cooling.

Give a daily-life example of cooling by evaporation.

Sweating: sweat absorbs body heat to evaporate, cooling the skin (hence cotton clothes help in summer).

Why is ice at 273 K more effective for cooling than water at 273 K?

Ice absorbs additional latent heat of fusion to melt, removing more heat from surroundings than water at the same temperature.

Which produces more severe burns, steam at 100 °C or boiling water at 100 °C?

Steam, because it releases latent heat of vaporisation on condensation, transferring more energy to skin.

Arrange air, water, and honey in increasing order of density.

Air < Water < Honey.

Why can a diver easily cut through water but not wood?

Intermolecular forces in liquids are weaker, allowing particles to move aside; solids have strong forces, requiring much more force to separate particles.

Explain why a gas fills any container completely.

Gas particles move randomly at high speed with negligible attraction, so they spread out to occupy all available space.

What property of liquids and gases makes them collectively called ‘fluids’?

Fluidity—the ability to flow and take the shape of their container.

Why do we smell hot, sizzling food from a distance more quickly than cold food?

Higher temperature increases kinetic energy of aroma particles, enhancing the rate of diffusion through air.

What is meant by ‘bulk phenomenon’ in boiling?

During boiling, particles throughout the entire liquid (bulk) gain enough energy to form vapour, not just those at the surface.

State two differences between boiling and evaporation.

Boiling: occurs at fixed boiling point, bulk phenomenon, requires external heat; Evaporation: occurs at any temperature below boiling point, surface phenomenon, may occur without external heating.