Class 9 Chemistry Chapter 5 Question Answer

Important Notes of Class 9 Chemistry Chapter 5 Question Answer English Medium written by Professor Mr. Shahid Suib. These notes are very helpful in the preparation of Physical States of Matter for students of the Class 9 Chemistry Chapter 5 Question Answer English Medium and these are according to the paper patterns of all Punjab boards.

Summary and Contents:
Topics which are discussed in the notes are given below:
  • Complete Exercise MCQs of Chapter No.5 Physical States of Matter
  • Complete Exercise Short Questions with Answers of Chapter No.5 Physical States of Matter
  • Define a diffusion of gas with an example.
  • Define effusion and give an example. (2023)
  • Define standard atmospheric pressure. Write its units.
  • Why are the densities of gases lower than that of liquids?
  • Why are the gases compressible?
  • What is absolute zero?  OR  What do you know about absolute zero temperature?
  • Does the Kelvin scale show a negative temperature?
  • What do you mean by condensation?
  • Why is the boiling point of water higher than that of alcohol?
  • What do you mean by dynamic equilibrium?
  • Define the boiling point of a liquid.
  • Define the freezing point of the liquid.
  • Define evaporation.
  • What do you mean by vapour pressure?
  • Define Boyle’s law. Write its mathematical form. (Also a long questions part).
  • Define Charles’s law. Write its mathematical form. (Also a long questions part)
  • Define the term allotropy with examples.
  • Define transition temperature and give an example. 
  • In which form Sulphur exits at 100 °C.
  • What are amorphous solids? Give an example.
  • What are crystalline solids? Give examples.
  • Convert the following units.
  • Why do atoms react?
  • Why is the bond between an electropositive and an electronegative atom ionic in nature?
  • Ionic compounds are solids. Justify.
  • More electronegative elements can form bonds between themselves. Justify.
  • Metals are good conductor of electricity. Why?
  • Ionic compounds conduct electricity in solution or molten form. Why?
  • What type of covalent bond is formed in nitrogen molecule.
  • Differentiate between lone pair and bond pair of electrons
  • Long Questions: 
  • Describe four factors that effect the diffusions of liquids.
  • Define boiling point and how it is affected by different factors.
  • Define vapour pressure and explain different factors on which is depends. 
  • Define evaporation. Explain the factors that effect on evaporation.
  • TYPICAL PROPERTIES: The process of changing of a liquid into a gas phase is called evaporation. It is reverse to condensation in which a gas changes into liquid. Evaporation is an endothermic process (heat is absorbed). Such as when one mole of water in liquid state is converted into vapour form, it requires 40.7 kJ of energy. In the liquid state, molecules are in a continuous state of motion. They possess kinetic energy but all the molecules do not have same kinetic energy. Majority of the molecules have average kinetic energy and a few have more than average kinetic energy.
  • Evaporation is a cooling process. When the high kinetic energy molecules vapourize, the temperature of remaining molecules falls down. To compensate this deficiency of energy, the molecules of liquid absorb energy from the surroundings. As a result the temperature of surroundings decreases and we feel cooling. For example, when we put a drop of alcohol on palm, the alcohol evaporates and we feel cooling effect. Evaporation depends upon following factors: 
  • Surface area: Evaporation is a surface phenomenon. Greater is surface area, greater is evaporation and vice verse. For example, sometimes a saucer is used if tea is to be cooled quickly. This is because evaporation from the larger surface area of saucer is more than that from the smaller surface area of a tea cup.
  • Temperature: At high temperature, rate of evaporation is high because at high temperature kinetic energy of the molecules increases so high that they overcome the intermolecular forces and evaporate rapidly. For example, water level in a container with hot water decreases earlier than that of a container with cold water. This is because the hot water evaporates earlier than the cold water.

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