The adjective I would use is apprehensive. In chapter two, the boys make many plans for their life on the island. They make rules and most the boys seem happy to be on the island. That is until Piggy mentions that they might be there for quite some time and the boys begin to grow sad. Then, one of the boys thinks he sees a beast in the forrest. The mood grows solemn. Overall, chapter two is all about introducing concepts that will be important later in the novel and foreshadowing the future mood/conflicts.
Fast food is convenient because it is cheap and it’s prepared ahead of time and you don’t need to cook it. You just order and enjoy the meal especially if you don’t know how to cook. It saves time and energy.