Stoichiometry grams to grams

              For the reaction represented by the equation $$N_2+3H_{2\ }\rightarrow\ 2NH_3$$  , how many moles of nitrogen (N2) are required to produce 18 grams of ammonia (NH3)?

For the reaction represented by the equation $$Pb\left(NO_3\right)_2+2KI\ \rightarrow\ PbI_2+2KNO_3$$  how many moles of lead iodide $$\left(PbI_2\right)$$ are produced of 300 grams potassium iodide $$\left(KI\right)$$  when $$Pb\left(NO_3\right)_2$$  is in excess?

For the reaction represented by the equation $$2KClO_3\rightarrow\ 2KCI+30_2$$  how many grams of potassium chlorate are required to produce 160. g of oxygen?