X, a shopkeeper, leaves a sealed 5 kilogram bag of a branded wheat flour at the door of Y with a note “you will like this quality wheat flour and pay Rupees 100 for this bag” without being asked to do so. Y on coming back, collects the bag from his door, opens the seal of the bag, and uses a quarter of kilogram for making chapattis (unleavened bread). But next day returns the bag. Is he bound to pay for the bag? He is