void OnMouseDown()
    {
        Debug.Log(objname);

        if (gotobjects <= 4)
        {
            if (tag == "exp-1")
            {
                expobject.GetComponent <SpriteRenderer>().enabled = true;
            }
            if (gotobjects == 4)
            {
                cl.AddScore();
                cl.SkipQuestion(21);
            }
        }

        if (gameObject.name == "exp-test_tube")
        {
            test_tube_plane.GetComponent <SpriteRenderer>().enabled = true;
            leaf.GetComponent <SpriteRenderer>().enabled            = false;
            leaf_plane.GetComponent <SpriteRenderer>().enabled      = true;
            cl.SkipQuestion(2);
        }
        else
        {
            gotobjects = gotobjects + 1;
        }
        Destroy(gameObject);
    }