Among the following which one has weakest carbon-halogen bond?

Among the following which one has bond order as 3?

Among the following which one has the shortest Cl-O bond length

Among the following the weakest base is .

Among the following the weakest base is

Among the following the weakest base is

Which among the following has the strongest and weakest ionic bond? Support your answer. in iodides of lithium,sodium,pottassium, cesium