Ok I may be young but combine the two reactions to create a compund
Answer:
RbI<RbBr<RbCl<RbF
Explanation:
As stated in the question, the latice energy depends on the relative size of the ions. When the action size is constant as in the question, the lattice energy now depends on the relative of the anions. The order of increase in ionic sizes among the halide ions is fluoride<Chloride<Bromide<Iodide. This order of increasing size means that the lattice energy will decrease accordingly as shown in the answer.
Electron transitions from higher to lower energy levels cause emission of energy in the form of electromagnetic waves, each with their own specific wavelength. Because the energy levels of elements are quantized, each transition has a specific energy difference. The collection of these transitions makes up the emission spectrum and each spectrum is unique to a specific element, allowing identification.