Matter in Our Surroundings
Q12. Give the best evidence for motion of particles in matter.
Which process provides the best evidence for the particle theory of matter?
Q13. Which property of liquids and gases tells us that their molecules are moving constantly?
Q14. Write the term that is used to describe the mixing of copper sulphate and water kept in a beaker, on its own?
Q15. Name the phenomenon in which particles of two or more substances intermix on their own.
Q16. Name two substances which undergo sublimation.
Ans. camphor or ammonium chloride
Q17. Which of the following are matters?
chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.
Ans. chair, air, almonds, and cold drink
Q18. Name the gas which is supplied in compressed form in homes.
Ans. liquefied petroleum gas (LPG)
Q19. Name the gas which is supplied to hospitals in cylinders in compressed form.
Q20. Which of the following is highly compressible?
Ans. Gases are highly compressible as compared to solids and liquids.
Q21. Suggest a method to liquefy atmospheric gases.
Ans. Gases can be liquefied by applying pressure and lowering temperature.
Q22. What is the temperature at which a liquid changes into a gas?
Ans. Temperature at which a liquid changes into a gas is the boiling point.
Q23. What is the temperature at which a solid changes into a liquid?
Ans. Temperature at which a solid changes into a liquid is the melting point.
Q24. Why are liquids called as fluid?
Ans. Liquids flow and change shape, so they are not rigid but can be called fluid.
Q25. The mass per unit volume of a substance is called density. (density = mass/volume). Arrange the following in order of increasing density – air, exhaust from chimneys, honey, water, chalk, cotton and iron.
Ans. Increasing density:
air < exhaust from chimneys < cotton < water < honey < chalk < iron
Q26. Write the full form of LPG and CNG.
Ans. LPG - Liquefied Petroleum Gas
CNG – Compressed Natural Gas
Q27. What is boiling point?
Ans. The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
Q28. What is melting point?
Ans. The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
Q29. Why boiling is considered a bulk phenomenon?
Boiling is a bulk phenomenon. Explain
Ans. Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain enough energy to change into the vapour state.
Q30. How can we change the physical states of matter?
Ans. State of matter can be changed into another state by changing the temperature and pressure.
Q31. What are the Five States of Matter?
Ans. Now scientists are talking of five states of matter: Solid, Liquid, Gas, Plasma and Bose-Einstein Condensate.
Q32. Under what conditions heat can be given to a substance without raising its temperature?
Ans. During the change of states heat can be given to a substance without raising its temperature.