a cylinder provided with a piston has more pcl5 which is in equilibrium with pcl3 and cl2.system is compressed with the help of piston . will the system remain unaffected

Hey student..
in this question you need to use the concept of le chattliers principle and the effect of volume change on the equilibrium..When any system at equilibrium is subjected to change in concentration, temperature, volume, or pressure, then the system readjusts itself to (partially) counteract the effect of the applied change and a new equilibrium is established.

A cylinder provided with a piston has some PCl 5​ which is in equilibrium with PCl 3​ and Cl 2​ . The system is compressed with the help of piston. PCl 3​ andCl 2​ will combine to form PCl 5​ . Due to this, the number of moles of gaseous species will decrease as 2 moles will combine to give 1 mole.This will decrease the pressure and nullify the effect of compressing the system.According to Le Chatelier`s principle, when a system at equilibrium is disturbed, the position of the equilibrium shifts in a direction so that the effect of the change is nullified.