Answer:
The correct answer will be " RbF > RbCl > RbBr > Rbl".
Explanation:
The size of the given ions will be:
RbCl:
⇒  689kJ/mol
RbBr:
⇒  660kJ/mol
Rbl:
⇒  630kJ/mol
RbF:
⇒  785kJ/mol
Now according to the size, the arrangement will be:
⇒  (785kJ/mol) > (689kJ/mol) > (660kJ/mol) >(630kJ/mol)
⇒  RbF > RbCl > RbBr > Rbl
The bond among all opposite charging ions seems to be strongest whenever the ions were indeed small.