What is the valency of :

(a) fluorine in $Ca{F}_2$ (b) sulphur in $S{F}_6$

(c) phosphorus in $P{H}_3$ (d) carbon in $C{H}_4$

(a) Fluorine in $Ca{F}_2$ → (+2)+2x=0
⇒2x=-2
⇒x=-2/2
⇒x=-1
∴The valency of Fluorine in $Ca{F}_2$ is '-1'.

(ii) Sulphur in $S{F}_6$ → x + 6(-1) = 0
⇒ x - 6 = 0
⇒ x = 6
∴The valency of Sulphur in $S{F}_6$ is '6'.

(iii) Phosphorus in $P{H}_3$ →x+3(1)=0
⇒x+3=0
⇒x=-3
∴The valency of Phosphorus in PH₃ is '-3'.

(iv) Carbon in $C{H}_4$ →x+4(1)=0
⇒x + 4 = 0
⇒x = -4
∴The valency of Carbon in $C{H}_4$ is '-4'.