 2 is formed when a mixture of fluorine and xenon gases is exposed to ultraviolet light . Ordinary daylight is sufficient . Long @-@ term heating of XeF 
 2 is formed when a mixture of fluorine and xenon gases is exposed to ultraviolet light . Ordinary daylight <a href='drop_aux' title='1'><mark>is</mark></a>sufficient . Long @-@ term heating of XeF 
2 is formed when a mixture of fluorine and xenon gases is exposed to ultraviolet light . Ordinary daylight sufficient . Long @-@ term heating of XeF