Matter in Our Surroundings
Frequently Asked Questions
Matter is anything that has mass and occupies space.
The three states of matter are solid, liquid, and gas.
Particles of matter have space between them, move continuously, and attract each other.
Gases can be compressed because their particles are far apart and can come closer on pressure.
Diffusion is the mixing of particles of two substances due to particle motion.
Solid state has definite shape and fixed volume.
Gaseous state has neither fixed shape nor fixed volume.
Liquids take the shape of the container they are kept in.
Because gases have very large intermolecular spaces between particles.
On heating, particles gain energy and move faster, increasing the distance between them.
The transformation of matter from one state to another, like solid to liquid, is change of state.
The constant temperature at which a solid melts to form a liquid is the melting point.
The constant temperature at which a liquid changes into a gas is its boiling point.
Sublimation is the process where a solid changes directly into gas without becoming liquid.
Camphor and ammonium chloride show sublimation.
Evaporation is the surface phenomenon by which liquids change into vapour at any temperature below their boiling point.
Surface area, temperature, humidity, and wind speed affect evaporation rate.
Sweat evaporates using body heat, causing a cooling effect.
Higher wind speed increases evaporation rate, drying clothes faster.
Condensation is the change of gas or vapour into liquid on cooling.
It is the heat energy required to change 1 kg of solid into liquid without temperature change.
It is the heat energy required to convert 1 kg of liquid into vapour without temperature change.
Ice’s density is lower than water because its particles are more spread apart.
During cooling, particles lose energy and move less vigorously.
It is the reversible change of matter from one state to another by heating or cooling.
Ice melting into water, and water vaporizing into steam.
Matter is made of tiny particles that are continuously moving.
Diffusion in gases is fast due to large spaces and high-speed moving particles.
Because liquid particles are closer and move less freely than gas particles.
Because their particles are tightly packed with strong intermolecular forces.
Gas particles move freely in all directions filling the whole container.
Deposition is the change from gaseous state directly to solid without forming liquid.
Freezing is the process of liquid changing into solid on cooling.
Steam condensing into water is gas to liquid change.
Humidity is the amount of water vapour present in the air.
High humidity slows down the rate of evaporation.
Ice has latent heat of fusion, so it absorbs heat without temperature change, feeling colder.
Temperature measures the degree of hotness or coldness of a body.
Higher temperature increases particle motion and kinetic energy.
On heating, particles vibrate more and occupy more space, causing expansion.
The SI unit of temperature is Kelvin (K).
Evaporation occurs at all temperatures, while boiling occurs at a fixed temperature.
At high altitude, atmospheric pressure is lower, so water boils at a lower temperature.
The normal boiling point of water is 100°C (373 K).
The normal melting point of ice is 0°C (273 K).
By change in temperature or pressure, matter can change its physical state.
Dry air increases evaporation rate, making the cooler more effective.
It is the energy due to motion of particles in matter.
Liquids have definite volume, but gases do not.
Increasing pressure can compress gases to liquids; decreasing pressure can reverse it.
