Wheatstone bridge

The arrangement of five capacitors as shown is called Wheat stone bridge.

If   then points P & Q are at same potential & the bridge is said to be balanced, due to this no charge will flow  in the arm PQ & hence arm  PQ can be removed &  circuit can becomes as shown.

The effective capacitance across the points X & Y for the balanced state of Wheatstone bridge is the bridge is not balanced, then the problem can be solved using Kirchoff’s laws.