How many milliliters of a stock solution of 2.00M KNO3 would you need to prepare 150mL of a 0.3M solution?

Can someone me with questions 12 and 13 plz.

How many moles are contained in 5.6 l of h2 at stp

The characteristics of two different types of reactions are shown below: reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.