Question

1.Which of the following would have permanent dipole moment- BF3, SF4, SiF4, XeF4 ......and WHY? 2. Order of Covalent character in SF4, SF2 and SF6??

Answer 1

BF3 is permanent dipole.due to absence of lone pair
order of CC :-
SF6>SF4>SF2

Answer 2

1. Out of the given options of Boron Trifluoride $\bold{\left(\mathrm{BF}_{3}\right)}$, Sulphur Tetrafluoride $\bold{\left(\mathrm{SF}_{4}\right)}$, Silicon Tetrafluoride $\bold{\left(\mathrm{SiF}_{4}\right)}$ and Xenon Tetrafluoride $\bold{\left(\mathrm{XeF}_{4}\right)}$, option Boron Trifluoride has permanent dipole moment because of the absence of lone pair of electron. $BF_3$ is used as a Lewis acid and in the synthesis of various organic compounds in the laboratory.

2. Order of $\bold{\mathrm{SF}_{4}, \mathrm{SF}_{2} \text { and } \mathrm{SF}_{6}}$ in accordance with covalent character is $\bold{\mathrm{SF}_{6}>\mathrm{SF}_{4}>\mathrm{SF}_{2}}$.