What do the lines around the finger of the doorknob represent?

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?

Acontrol during an experiment. might change remains constant does not exist does change

If one fission reaction of a uranium-235 atom produced two neutrons, how many neutrons would be released if the chain reaction occurred three more times?