Destroy object when it is in space for certain time continously

Thank you for the answer.. I have written this code but time is not effecting as i want.. wehnever it is lightly above the ground it call the loose method but when it again comes to ground player again continuous playing the game.....i want that if the object leaves the ground for certain time only then object destroys.....

 public int time=5;
 void OnTriggerExit(Collider col)
         {
             if (grounded == false) 
             {
                 Destroy (gameObject, time);
                 loose();
             }
         }
         void loose()
         {
             countText.text = "!!!TRY AGAIN!!!";
         }