An electron moved from a lower energy level to a higher energy level. What most likely happened during the transition

Idon’t know how to solve this question

In 1901, thomas edison invented the nickel-iron battery. the following reaction takes place in the battery. fe(s) + 2 nio(oh)(s) + 2 h2o(l) fe(oh)2(s) + 2 ni(oh)2(aq) how many mole of fe(oh)2, is produced when 5.35 mol fe and 7.65 mol nio(oh) react?

Consider the elements bromine and chlorine; which elements has a larger ionic radius ?