Directions : These questions consist of two statements each printed as Assertion and Reason. While answering these questions you are required to choose any one of the following four responses Assertion: One end of a massless rod of length l is hinged, so that it is free to rotate in a vertical plane about a horizontal axis. If a particle is attached to the other end of the rod, then the minimum speed at  lower most position of the particle is 5gl tocomplete the circular motion. Reason : Work done by centripetal force on the particle is always zero.