Properties of Matter Physic 9 Cha 7 Bise Rawalpindi

Bise Rawalpindi Physic Chapter 7 Properties of Matter Notes questions answer MCQs Urdu Medium and English Medium Pdf Download.

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chapter 7 physics class 9 pdf download

i) In which of the following states molecules do not leave their position?

  • A. solid  
  • B. liquid
  • C. gas
  • D. plasma

ii) Which of the substances is the lightest one?

  • A. copper 
  • B. mercury
  • C. aluminum
  • D. lead

Properties of Matter G9 Physics Notes Pdf Download Bise Rawalpindi

How is the kinetic molecular model of matter helpful in differentiating various states of matter?

According to the kinetic molecular model, solids have small intermolecular distances and strong forces of attraction. In liquids, intermolecular distance is greater than solids but smaller than gasses and forces are weak. In the case of gasses, intermolecular distance is very large, and hence the very weak force of attraction exists between them. This helps to differentiate between solids, liquids, and gasses.

Q.3) Does there exist a fourth state of matter? What is that?

Answer:

Yes, the fourth state of matter exists which is known as plasma. When the temperature of a gas is increased enough to eject electrons from the atoms of the gas, the gas is ionized. This ionized gas is known as plasma.

Q.4) What is meant by density? What is its SI unit?

Answer:

DENSITY

The mass per unit volume is called density

Its S.I unit is kgm-3.

Q.5) Can we use a hydrometer to measure the density of milk?

Answer:

Yes, we can use a hydrometer to measure the density of milk because the hydrometer is an instrument that is used to measure the density of liquids.

Q.6) Define the term pressure.

Answer:

PRESSURE

Force per unit area is called pressure

The S.I unit of pressure is the pascal (Pa)

Q.7) Show that the atmosphere exerts pressure.

Answer:

In the atmosphere of the earth, there are gasses, water vapor, and dust particles. Due to the force of gravity acting on these particles, the object inside the atmosphere experiences pressure all around equally.

Q.8) It is easy to remove air from a balloon but it is very difficult to remove air from a glass bottle. Why?

Answer:

This is because the air inside the balloon is at a higher pressure than the atmospheric pressure outside the balloon. In the case of a glass bottle, the air pressure inside the glass bottle is already equal to atmospheric pressure. So, it is difficult to remove air from a glass bottle.

Q.9) What is a barometer?

Answer:

The barometer is a device to measure the pressure of the air.

One of the simple barometers is a mercury barometer.

Q.10) Why is water not suitable to be used in a barometer?

Answer:

Water has a smaller density. Therefore, the height of the water column in the tube of the barometer would be very large, about 10 m, which is not convenient as a glass tube of length more than 10 m is required to make a water barometer. That’s why they use of water in the construction of a barometer is not suitable.

Q.11) What makes a sucker pressed on a smooth wall stick to it?

Answer:

When the sucker is pressed on a smooth surface, the air pressure below it becomes very small as compared to the air pressure above it. This helps to stick it with a smooth surface. If the wall is not smooth, air would slowly seep into the sucker through the microscopic gaps between the edges of the sucker and the wall and the sucker will detach from the wall.

Q.12) Why does atmospheric pressure vary with height?

Answer:

When we move away from the earth, the density of air decreases as a result atmospheric pressure also decreases. At very high positions the density of air is very small. So due to this reason, the atmospheric pressure of air varies with height.

Q.13) What does it mean when the atmospheric pressure at a place falls suddenly?

Answer:

When the pressure of the atmosphere falls suddenly, it means that the intermolecular distance of air molecules increases. So their energy decreases and as a result, the temperature decreases. As a very loose rule, a high-pressure area will be clear and a low-pressure area will be cloudy and rainy.

Q.14) What changes are expected in weather if the barometer reading shows a sudden increase?

Answer:

The weather of a place changes if the atmospheric pressure of that place changes. When the barometer reading shows sudden change, it means the pressure of the air increases, so the air molecules bring close and their energy also increases. Hence, the temperature of that place rises and the wind blows from areas of high pressure to areas of low pressure. The intensity of the storm depends on the difference in pressure.

Q.15) State Pascal’s law.

Answer:

Pascal’s law states that the fluid exerts pressure equally in all directions.

This law holds for all fluids i.e. both liquids and gasses.

Q.17) What is meant by elasticity?

Answer:

The property of a body to regain its original size and shape after the deforming force is removed is known as elasticity.

Q.18) State Archimedes principle.

Answer:

Archimedes principle states;

“When an object is totally or partially immersed in a liquid, an upthrust acts on it equal to the weight of the liquid it displaces.”

Q.19) What is upthrust? Explain the principle of floatation

Answer:

UPTHRUST

The fluid exerts force in the upward direction when some object is immersed in them. This is called upthrust.

PRINCIPLE OF FLOATATION

If the weight of the fluid displaced is equal to the weight of floating objects inside the liquid. Then the object will not sink and keep floating. It is called the principle of floating.

Q.20) Explain how a submarine moves up the water surface and down into the water.

Answer:

A submarine works on the principle of floatation. It floats over water when the weight of the submarine is less than or equal to the upthrust of water. It has a system of tanks that are empty. When these tanks are filled with seawater, the weight of the submarine increases. As soon as its weight becomes greater than the upthrust, it dives into the water and moves underwater. To come to the surface, tanks have to be empty.

Q.21) Why does a piece of stone sink in water but a ship with a huge weight floats?

Answer:

It is due to the Archimedes principle. The density of the ship is less, it displaces more liquid and experiences more upthrust and floats. Whereas the density of stone is more, it displaces less liquid and experiences less upthrust and sinks.

Q.23) Take a rubber band. Construct a balance of your own using a rubber band. Check its accuracy by weighing various objects.

Answer:

Take a rubber band and hang it with a hook. Then the pointer is attached to its lower end with a scale in front of the pointer. Different known weights are suspended one by one at the lower end of the rubber band. The pointer position on the scale is marked for each weight. It is called the calibration of scale for weight measurement. This makes a balance for weight measurement.