How to prevent a spawn if my ray is on a certain object?

Questions & Answers
1

Here is my code:
using UnityEngine;
using System.Collections;

public class Instantiate : MonoBehaviour {
	//position and rotation can be equal to that of an object if you use the object's ID.
	Ray ray;
	RaycastHit hit;
	public GameObject Sphere;

	void Update ()
	{
			ray = Camera.main.ScreenPointToRay (Input.mousePosition);
		if (Physics.Raycast (ray, out hit))
		{
			if (Input.GetMouseButtonDown (0))
			{
				Instantiate (Sphere, hit.point + new Vector3(0, 0.5f, 0), Quaternion.identity);

			}
		}
	}
}

How can I make it so that when the ray hits a sphere clone, the instantiation code does not execute? Keep in mind that I am new to Unity, so try to use simple terms on me.

2

It’s actually really simple: All you have to do is to test if your raycast is hitting the sphere clone. We can do this simply by checking if the name of the object we’ve hit is "Sphere (clone):

public class Instantiate : MonoBehaviour {
	//position and rotation can be equal to that of an object if you use the object's ID.
	Ray ray;
	RaycastHit hit;
	public GameObject Sphere;
	
	void Update ()
	{
		ray = Camera.main.ScreenPointToRay (Input.mousePosition);
		if (Physics.Raycast (ray, out hit))
		{
			if (Input.GetMouseButtonDown (0))
			{
				if(hit.transform.name == "Sphere (Clone)")
				{
					Instantiate (Sphere, hit.point + new Vector3(0, 0.5f, 0), Quaternion.identity);
				}
			}
		}
	}
}