Among the following, the number halide(s) which is / are inert to hydrolysis is ______.
(i) BCl3 (ii) SiCl4 (iii) PCl5 (iv) SF6
(1) BCl3+3H2O→H3BO3+3HCl (2) SiCl4+4H2O→SiO4H4+4HCl (3) PCl5+H2O→POCl3+2HCl
(4) Due to steric crowding by six F-atoms, SF6 is inert towards hydrolysis.