MATTER IN OUR SURROUNDINGS class IX and key

Chapter 1: Matter in Our Surroundings

MATTER IN OUR SURROUNDINGS (notes)

 MATTER IN OUR SURROUNDINGS (problems )

   Matter in Our Surroundings (key)

• Matter is made up of particles
• The particles of matter are very small-they are small beyond our imagination
• Particles of matter have space between them
• Particles of matter move continuously in liquids and gases.
• Matter exists in three states i.e., solid, liquid and gas
• The force of attraction between the particles are maximum in solids, intermediate in liquids and minimum in gases.
• The particles are arranged orderly in the case of solids while  particles move randomly in gasses.
• Diffusion is possible only when particles of matter move continously.
• Rate of diffusion of gases is higher than that of liquids (or) solids.
• The states of matter are not permanent. The state of matter can be changed by changing temperature or pressure.
• Evoparation is a surface phenomenon because particles from the surface gain enough energy to overcome the forces of attraction present in the liquid and change into the vapour state.
• Boiling is a bulk phenomenon because particles of the entire liquid change into vapour state.
• Changes in temperature, surface area and wind speed effect rates of evaporation.
• Humidity is the amount of water vapour present in air.