WHAT is the valency of - fluorine in CaF2 , Sulphur in SF6 , PHOSPHORUS in PH3 , carbon in CH₄

Q. What is the valency of phosphorus in $P{H}_3$?

Q. The valency of fluorine in $Ca{F}_2$ is :

Q. The valency of sulphur in $S{F}_6$ is :

Q. What is the valency of carbon in $C{H}_4$?

Q. Buckminsterfullerene is an allotropic form of the element :
(a) phosphorus (b) fluorine (c) carbon (d) sulphur