At the initial stage globe and syringe body is in one unit.the total volume of the unit is (700+400) = 1100ml and pressure is 50kpa.

When the piston pushed in the volume incorporated with the syringe body will be removed from the system.Finally the unit will remain with the volume of the globe(700ml) only.Since there is a change in the volume of the unit pressure will also be changed.

Using Boyle's law

`P_1V_1 = P_2V_2`

`50*1100 = P_2*700`

       `P_2 = 78.57kpa`

So the pressure of the final system will be 78.57kpa.

Assumptions

• The gas is a ideal gas
• There is no temperature change within the process