Calculate the mass of Ba(OH)2 required to prepare 0.723M solution dissolved in 4,807mL of water.

Combustion is the act or process of burning. therefore, i believe the answer is  a: burning wood. 

It is a ok  i know i have a brain functioning well.                                                                                                                                                           

Remember that rust prevented by placing a sacrificial electrode in electrical contact with the iron. the sacrificial electrode must be composed of a metal that  oxidizes  more easily than iron (that is, it must be below iron in table 18.1).