Who is really good with chemistry and can help me with some questions/equations? I also have more i really don't get this subject

What is a metal replacement reaction

How many moles of oxygen gas are produced from the decomposition of six moles of potassium chlorate

Which statement best summarizes the importance of ernest rutherford’s gold foil experiment? it proved that all of john dalton’s postulates were true. it verified j. j. thomson’s work on the atomic structure. it showed that an electron circles a nucleus in a fixed-energy orbit. it showed that a nucleus occupies a small part of the whole atom.