Class 9th Physics Chapter 7 Question Answer

Complete Notes of Class 9th Physics Chapter 7 Question Answer Properties of Matter Numericals in 9th Class Physics Urdu Medium written by Sir Fahad Abbas Suib. These computerized notes are very helpful in the preparation of Properties of Matter Numericals for students of the Class 9th Physics Chapter 7 Question Answer these are according to the paper patterns of all Punjab boards.

• Important Values and Important Formulas
• Properties of Matter Exercise Numericals with Solutions in Urdu 
• Explain that to fix a thumb pin, pressure exerted on the top increases thousands time on the pin point.
• Explain the use of Hydrometer to measure the density of a car battery acid.
• Explain that ships and submarines float on sea surface when the buoyant force acting on them is greater than their total weight.
• State that Hydraulic Press, Hydraulic car lift and Hydraulic brakes operate on the principle that the fluid pressure is transmitted equally in all directions.
• Explain that the action of sucking through a straw, dropper, syringe and vacuum cleaner is due to atmospheric pressure.
• Matter exists in three states, solid, liquid and gas. There are many properties associated with matter. For example, matter has weight and occupies space. There are some other properties which are associated with one state of matter but not with other. For example, solids have shape of their own while liquids and gases do not. Liquids on the other hand have definite volume while gases do not have. Various materials differ in their hardness, density, solubility, flow, elasticity, conductivity and many other qualities. Kinetic molecular model helps in understanding the properties of matter in a simplified way.
• KINETIC MOLECULAR MODEL OF MATTER: The kinetic molecular model of matter has some important features. These are
• Matter is made up of particles called molecules.
• The molecules remain in continuous motion.
• Molecules attract each other. Kinetic molecular model is used to explain the three states of matter - solid, liquid and gas. 
• SOLIDS: Solids such as a stone, metal spoon, pencil, etc. have fixed shapes and volume. Their molecules are held close together such by strong forces of attraction. However, they vibrate about their mean positions but do not move from place to place.
• LIQUIDS: The distances between the molecules of a liquid are more than in solids. Thus, attractive forces between them are weaker. Like solids, molecules of a liquid also vibrate about their mean position but are not rigidly held with each other. Due to the weaker attractive forces, they can slide over one another. Thus, the liquids can flow. The volume of a certain amount of liquid remains the same but because it can flow hence, it attains the shape of a container to which it is put.
• GASES: Gases such as air have no fixed shape or volume. They can be filled in any container of any shape. Their molecules have random motion and move with very high velocities. In gases, molecules are much farther apart than solids or liquids. Thus, gases are much lighter than solids and liquids. They can be squeezed into smaller volumes. The molecules of a gas are constantly striking the walls of a container. Thus, a gas exerts pressure on the walls of the container.
• PLASMA - THE FOURTH STATE OF MATTER: The kinetic energy of gas molecules goes on increasing if a gas is heated continuously. This causes the gas molecules to move faster and faster. The collisions between atoms and molecules of the gas become so strong that they tear off the atoms. Atoms lose their electrons and become positive ions. This ionic state of matter is called plasma. Plasma is also formed in gas discharge tubes when electric current passes through these tubes. Plasma is called the fourth state of matter.
• A plasma bulb which a gas occurs in its ionic state. Positive ions and electrons get separated in the presence of electric or magnetic fields. Plasma also exists in neon and fluorescent tubes when they glow.