What is one of the ways a fission reaction can get out of control?

Answer : When the nuclear reaction produces too many neutrons.

Explanation : In a nuclear fission reactor where the reaction is controlled by regulating the number of neutrons produced by the chain reaction. Production of too many neutrons may cause an accelerated uncontrolled chain reaction which may cause enormous heat to be generated in a very short period of time inside the reactor which may result into an explosion.

For, this purpose control rods, made of neutron absorbing species, like cadmium, are placed in the nuclear reactors to control the excess number of neutrons at any point of reaction when required.

- aluminum and copper chloride.

- the chloride ion to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).