Which of the following statement is correct ?

$\therefore$In CF₄ No formation of back $\mathrm{\pi }$-bonds

In SiF₄, due to the availability of empty d-ortials it involes in back π bonding formation with fluorine lonepair electrons and hence the Si-F bond aquires double bond character.
$\therefore$Si-F bond is Strong where as in case of CF₄ C-F bond, do not aquires double bond character due to lack of empty d-ortials in the valency shell of carbon.therefore C-F bond is always single bond.