If a football hits an object thrown on pitch and deflects into goal?

Answer 1

FIFA Laws of the Game:

Law 9: The ball in and out of play

The ball is out of play when:

- it has wholly crossed the goal line or touch line whether on the ground or in the air

- play has been stopped by the referee

Law 10: Goal scored

A goal is scored when the whole of the ball passes over the goal line, between the goalposts and under the crossbar, provided that no infringement of the Laws of the Game has been committed previously by the team scoring the goal.

So, if the referee doesn't stop the play (althought he should when he realizes foreign object or an invader has entered the pitch) and a scoring team doesn't infringe the rules, the goal is valid.