In the system,CaF2s⇌Ca+2  aq + 2 F-  aq  , on increasing the concentration of Ca2+ions 4 times their initial value will causethe equilibrium concentration of F-ions to change

K1=Ca+2F-2; Let Ca+2=F-=1M; K1=1; K2=4 × x2,but KC remains constant 4x2 = 4× x2, x2 =14, x=12To keep Kc  constant , the concentration of F- should be made 12 of its initial value.