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