Only iodine forms hepta-fluroide `IF_(7)`, but chlorine and bromine give penta-flurorides. The reason for this is:

Only iodine forms hepta -fluoride IF_(7) , but chlorine and bromine give penta -fluorides.The reason for this is

(A) Iodine oxides are more stable than chlorine and bromine oxides (R ) Iodine is the solid halogen ,but chlorine and bromine are gaseous and liquid halogens

Give reasons for the following Chlorine displaces bromine from potassium bromide.

Chlorine bromine , iodine are Dobereiner's triads .How do you justify ?