The object ball refers to both the first ball hit by the cue ball and refers to the ball intended to be pocketed, depending upon how the term is used. In most cases, it refers only to the ball that is to be pocketed.
The 8 ball
If the black 8 ball is the object ball and a foul occurs during the shot, the game is over. This foul is loss of game.
depends on the game, most common are 8-ball in which there are 15.one player plays1-7, the other plays 9-15,then the 8. the other is 9-ball in which there 9. In 9 ball pool you hit the nine ball in last.10 or 16. The three most common pool games are 8 Ball, 9 Ball and Straight Pool. Both 8 Ball and Straight Pool use 15 numbered balls and the cue ball. In 9 Ball, only the first 9 numbered balls are used plus the cue ball.
8
That is lose of game.
This depends on the specific rules of the game you play. Under BCA and APA Rules the other player gets ball-in-hand.
Pool
The fifth ball in a pool ball triangle will dpend upon the game being played. In Straight Pool, it can be any of 13 different balls. Only the 1 and the 5 cannot be located there. In 8 Ball, the 5th ball must be the 8 ball.
you need to play the game :
Unless you are supposed to be aiming for the 8 ball, pocketing the 8 ball at any point in the game results in loss.
All pool games require that certain balls be identified. If you chose to use a custom set of pool balls with only the markings necessary for a particular game, it would not be contrary to the regulations to do so.
There are 8 coloured balls in a standard game of pool (the 1 through 7 and the 8 ball), and there are 7 striped balls. That sums to 15 balls.