**Observation:**

When force is applied and then removed on the plunger of a syringe containing air, the following observations can be made:

1. **Compression of Air:** When force is applied on the plunger, it moves inward, reducing the volume inside the syringe. As a result, the air inside the syringe gets compressed.

2. **Resistance to Compression:** Initially, the air inside the syringe offers some resistance to compression. This is because air is a gas and its particles are widely spaced. When force is applied, the particles come closer together, causing them to collide with each other and the walls of the syringe. This collision produces resistance to compression.

3. **Increase in Pressure:** As the volume of the air decreases due to compression, the pressure inside the syringe increases. This increase in pressure can be observed by the pressure gauge attached to the syringe or by the resistance experienced while pushing the plunger.

4. **Expansion of Air:** When the force is removed from the plunger, it moves outward, increasing the volume inside the syringe. As a result, the compressed air expands to occupy the increased volume.

5. **Decrease in Pressure:** As the volume of the air increases, the pressure inside the syringe decreases. This decrease in pressure can be observed by the pressure gauge or by the ease with which the plunger can be pulled out.

6. **Cooling Effect:** During the compression of air, some of the energy of the moving particles is converted into heat energy, causing the temperature of the air to increase slightly. When the compressed air expands, it absorbs heat from the surroundings, resulting in a cooling effect. This can be observed by touching the syringe, which feels cool when the plunger is pulled out.

7. **Reversibility:** The process of compression and expansion of air is reversible. When force is applied, the air compresses, and when the force is removed, the air expands back to its original volume. This indicates that the changes in volume, pressure, and temperature are reversible in the case of air.

In conclusion, when force is applied and then removed on the plunger of a syringe containing air, compression and expansion of air occur, leading to changes in volume, pressure, and temperature.

We see that the plunger can easily insert in the syringe ,this shows that the air or gas inside the syringe compress easily when the pressure is applied. Hope it will help you!!!!