A first-order reaction has a rate constant of 0.241/minmin. If the initial concentration of A is 0.859 MM, what is the concentration of A after 10.0 minutes? View Available Hint(s)

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.