on trigger enter

In my game i have ten ball hanging in the air which is tagged as ball.I have a cube in the ground.Here i am using on trigger enter my problem is when each ball hit the cube i want to destroy the particular falling ball on the cube.I want to destroy the particular ball which is on trigger with cube which is placed in ground and want the rest of hanging balls to be in there position with out destroy.But any ball can fall on this cube according to that i want to destroy the ball.

Attach this script to the cube (or add this code to the cube script, if any):

function OnTriggerEnter(thing: Collider){
  if (thing.tag == "ball"){

The ball which touched the trigger will be killed. For this to work, the ball must be tagged “ball” (tags are case sensitive!) and have a collider.