How to check if there´s an object at position

Hi, I have this code:

function OnCollisionEnter(collision : Collision)
{
  
   Instantiate (chunk, Vector3(transform.position.x,transform.position.y ,transform.position.z + 7),Quaternion.identity) ;
  
   Instantiate (chunk, Vector3(transform.position.x,transform.position.y ,transform.position.z - 7),Quaternion.identity) ;

   Instantiate (chunk, Vector3(transform.position.x+7,transform.position.y ,transform.position.z ),Quaternion.identity) ;

   Instantiate (chunk, Vector3(transform.position.x-7,transform.position.y ,transform.position.z ),Quaternion.identity) ;
   
}

This creates an object every time i collide with an object like it in 4 different positions, the problem is that when i collide with an object that has already an object next to it it creates an object again in the same place so this causes the game to freeze.

I need a code to check if there´s an object at a position and if there´s not then execute my code. Hope you can help me

I would say that there are multiple ways of solving this. One would be this, though that isn’t the solution I would normally use.
If your chunks have colliders I would probably just go for using a Raycast and sending a ray in each direction to see if it hits an already pre-existing chunk (or any other obstacle really) with a layer mask.