Well, to answer that, we need to know more about the 'Impossible' you're referring to. Is it a film, a novel, or something else? If it's a work of fiction, chances are it's not a true story. But if it's a documentary or based on real people's experiences, then it could be.
It's not straightforward to determine. 'Impossible' could refer to events that are rare or unlikely in real life but not necessarily untrue. Or it could just be a fictional creation with no basis in reality at all.
Partly. While the main events and the overall situation are based on real incidents, some elements might have been fictionalized or dramatized for the sake of the story.
Yes, it is. The movie is based on the true events that occurred during the tsunami disaster. It portrays the struggles and survival of a particular family in that terrifying situation.